Daesung Lee - Academia.edu (original) (raw)
Papers by Daesung Lee
A novel bioluminescence-based method to investigate uptake of bile acids in living cells
American journal of physiology. Gastrointestinal and liver physiology, 2018
Bile acid transporters, including the ileal apical sodium-dependent bile acid transporter (ASBT) ... more Bile acid transporters, including the ileal apical sodium-dependent bile acid transporter (ASBT) and the hepatic sodium-taurocholate cotransporting polypeptide (NTCP), are crucial for the enterohepatic circulation of bile acids. Our objective was to develop a method for measuring bile acid transporter activity in real time to precisely evaluate rapid changes in their function. We designed a reporter system relying on a novel probe: cholic acid attached to luciferin via a disulfide-containing, self-immolating linker (CA-SS-Luc). Incubation of human embryonic kidney-293 cells coexpressing luciferase and ASBT with different concentrations of CA-SS-Luc (0.01-1 μM) resulted in bioluminescence with an intensity that was concentration- and time-dependent. The bioluminescence measured during incubation with 1 μM CA-SS-Luc was dependent on the levels of ASBT or NTCP expressed in the cells. Coincubation of CA-SS-Luc with natural bile acids enhanced the bioluminescence in a concentration-depen...
ChemInform Abstract: Total Synthesis of (3R,9R,10R)-Panaxytriol via Tandem Metathesis and Metallotropic [1,3]-Shift as a Key Step
ChemInform
ABSTRACT ChemInform is a weekly Abstracting Service, delivering concise information at a glance t... more ABSTRACT ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Synthesis of Novel Taxol Analogues and Evaluation of Their Biological Activities
ChemInform
ABSTRACT
Orthogonal lipid sensors identify transbilayer asymmetry of plasma membrane cholesterol
Nature chemical biology, Mar 26, 2016
Controlled distribution of lipids across various cell membranes is crucial for cell homeostasis a... more Controlled distribution of lipids across various cell membranes is crucial for cell homeostasis and regulation. We developed an imaging method that allows simultaneous in situ quantification of cholesterol in two leaflets of the plasma membrane (PM) using tunable orthogonal cholesterol sensors. Our imaging revealed marked transbilayer asymmetry of PM cholesterol (TAPMC) in various mammalian cells, with the concentration in the inner leaflet (IPM) being ∼12-fold lower than that in the outer leaflet (OPM). The asymmetry was maintained by active transport of cholesterol from IPM to OPM and its chemical retention at OPM. Furthermore, the increase in the IPM cholesterol level was triggered in a stimulus-specific manner, allowing cholesterol to serve as a signaling lipid. We found excellent correlation between the IPM cholesterol level and cellular Wnt signaling activity, suggesting that TAPMC and stimulus-induced PM cholesterol redistribution are crucial for tight regulation of cellular ...
Organic letters, Aug 22, 2016
A new benzannulation reaction with accompanied trifluoromethylthiolation is described. This benza... more A new benzannulation reaction with accompanied trifluoromethylthiolation is described. This benzannulation can generate a range of trifluoromethylthiolated benzolactams and benzolactones from 1,3,8-triynes and a stoichiometric amount of AgSCF3 at 90 °C through an initial Alder-ene reaction, 1,4-addition of AgSCF3, and a series of bond-reorganization processes that include double bond migration, 6π-electrocyclization, and a [1,3]-H shift. For certain substrates containing a triisopropylsilyl (TIPS) group, the final [1,3]-H shift-interrupted products, were obtained.
Initiation and Termination Mode of Enyne Cross-Metathesis and Metallotropic [1,3]-Shift Controlled by Remote Substituents
Journal of the American Chemical Society, Jul 7, 2010
The cross-metathesis of terminal alkyne and alkene using Ru-based Grubbs catalyst generally under... more The cross-metathesis of terminal alkyne and alkene using Ru-based Grubbs catalyst generally undergoes alpha-insertion. In this study, excellent control over alpha- and beta-insertion of ruthenium alkylidene into terminal alkynes has been achieved by using a substituent at a remote site from the reaction center. While the origin of this regioselectivity of insertion and metallotropic shift remains to be established, the trend indicates that the alpha-insertion with a concomitant metallotropic shift is favored with small substituents whereas the beta-insertion without a metallotropic shift is favored with bulky substituents such as tert-butyl and trialkyl silyl groups.
Organic Letters, Nov 1, 2001
A novel reaction between 1,3-dienes and selenium dioxide to give syn 1,2-and 1,4-diol cyclic sele... more A novel reaction between 1,3-dienes and selenium dioxide to give syn 1,2-and 1,4-diol cyclic selenites was studied in detail. This study indicates that an initial concerted [4 + 2] cycloaddition followed by a stereospecific carbon−selenium bond oxidation is involved in this unprecedented syn dihydroxy addition reaction mediated by selenium dioxide. The formation of a diol from an alkene is an important transformation in organic chemistry. 1 Usually, the syn addition of dihydroxy groups is achieved by OsO 4 , 2 RuO 4 , 3 and MnO 4 , 4 whereas anti addition is brought about by other oxides such as SeO 2 5 and WO 3. 6 In our investigations of the reaction between SeO 2 and 1,3-dienes, a novel reactivity profile of SeO 2 was observed, affording syn 1,2-and 1,4diols and selenophene. Treatment of diene 1, containing a carbonyl group at the C-1 position, with SeO 2 led to the formation of selenophene 2, whereas the analogous diene 3, containing a TBS-ether, yielded 1,4-diol cyclic selenite 4 and 1,2-diol cyclic selenite 5 (Scheme 1). Notably, the conversion of 3 to 4 involves an unprecedented direct oxidation of a C-Se bond to a CO bond, a transformation known to be difficult. 7 In this account, we elucidate the nature (1) (a) Haines, A. H. In ComprehensiVe Organic Synthesis; Trost, B.
![Research paper thumbnail of Cross and Ring-Closing Metathesis of 1,3-Diynes:� Metallotropic [1,3]-Shift of Ruthenium Carbenes](https://attachments.academia-assets.com/74936588/thumbnails/1.jpg)
](J Am Chem Soc, 2005
Metathesis reactions O 0286 Cross and Ring-Closing Metathesis of 1,3-Diynes: Metallotropic [1,3]-... more Metathesis reactions O 0286 Cross and Ring-Closing Metathesis of 1,3-Diynes: Metallotropic [1,3]-Shift of Ruthenium Carbenes.-The cross metathesis of 1,3-diynes with alkenes proceeds with excellent regioselectivity. It does not depend on the substituents of the alkynes in contrast to the (E)/(Z)-selectivity. The ring-closing metathesis of ene-1,3-diynes provides products that contain fully conjugated 1,5-dien-3-yne moieties which are formed by ring closure and followed by facile metallotropic [1,3]-shift.-(KIM, M.; MILLER,
Overcoming catalytic bias
Nature, 2011
ChemInform Abstract: Regio‐ and Stereoselectivity in the Concatenated Enyne Cross Metathesis—Metallotropic [1,3]‐Shift of Terminal 1,3‐Diyne
Tetrahedron, Mar 11, 2014
Advances in the metallotropic [1,3]-shift of alkynyl carbenoids
Org Biomol Chem, 2007
Metal complexes of alkynyl carbenes undergo a [1,3]-bond shift known as a metallotropic shift. Si... more Metal complexes of alkynyl carbenes undergo a [1,3]-bond shift known as a metallotropic shift. Since the discovery of the metallotropic [1,3]-shift of Rh-carbenoid, many more alkynyl carbene complexes with Ti, Cr, Mn, Mo, Ru, W, Re, Pt, and Au have been discovered to show metallotropic shift behavior. This article briefly summarizes the [1,3]-bond shift of alkynyl carbenes and their metal complexes.
Journal of the American Chemical Society, Jul 1, 2009
The insertion of alkylidene carbenes into C-H bonds is a powerful synthetic tool for constructing... more The insertion of alkylidene carbenes into C-H bonds is a powerful synthetic tool for constructing stereochemically defined quaternary carbon centers. 1 Various forms of alkylidene carbene species, including 1-4, have been studied for their reactivity and employed in natural product syntheses. 2 In general, the C-H bonds become more reactive toward carbene insertion if an oxygen atom is directly connected to the reacting C-H bond. 3 However, how the oxygen atom activates the C-H bonds toward insertion or how much it contributes to the reactivity of the C-H bonds in 2 and 3 relative to that in 1 has not been elucidated.
Synthesis of the Carbocyclic Core of Massadine
Organic letters, Jan 6, 2015
The carbocyclic core of massadine has been synthesized relying on a stereoselective formal [3 + 2... more The carbocyclic core of massadine has been synthesized relying on a stereoselective formal [3 + 2] cycloaddition of lithiumtrimethylsilyldiazomethane with α,β-unsaturated esters to form a Δ(2)-pyrazoline moiety followed by facile N-N bond cleavage. A unique feature of the current approach is the direct installation of the tertiary α-amino center and a β-cyano group in a cis arrangement on the resulting cyclopentane framework via a previously developed formal aminocyanation protocol.
Oxidative Dimerization of Silylallenes via Activation of the Allenic C(sp(2))-H Bond Catalyzed by Copper(I) Chloride and N-Hydroxyphthalimide
Organic letters, Jan 2, 2015
Novel oxidative dimerization of silylallenes is described. Treatment of silylallenes with a catal... more Novel oxidative dimerization of silylallenes is described. Treatment of silylallenes with a catalytic amount of copper(I) chloride, a substoichiometric amount of N-hydroxyphthalamide, and a stoichiometric amount of a terminal oxidant diacetoxyiodobenzene afforded head-to-head dimers as the main products. Silyallenes containing a small ring afforded only dimers, whereas as the ring size increased 1,3-enynes became more favorable products. For silylallenes containing an acyclic substituent, dimer formation is a norm with exceptions where N-hydroxyphthalimide reacts at the propargylic center to generate the corresponding aminoxy ethers.
Mechanistic Understanding of the Divergent Cyclizations of o-Alkynylbenzaldehyde Acetals and Thioacetals Catalyzed by Metal Halides
Chemistry (Weinheim an der Bergstrasse, Germany), Jan 14, 2015
Invited for the cover of this issue are the groups of Yuanzhi Xia at Wenzhou University (P.R. Chi... more Invited for the cover of this issue are the groups of Yuanzhi Xia at Wenzhou University (P.R. China) and Daesung Lee at University of Illinois at Chicago (USA). The image depicts the mechanistic understanding of the regiodivergent cyclizations of- o-alkynylbenzaldehyde acetals and thioacetals catalyzed by metal halides. Read the full text of the article at 10.1002/chem.201502469.
ChemInform Abstract: Regio-and Stereoselective Metal-Catalyzed Reactions and Their Application to a Total Synthesis of (-)-Dactylolide
ChemInform
ChemInform Abstract: Benzannulation of Triynes to Generate Functionalized Arenes by Spontaneous Incorporation of Nucleophiles
ChemInform, 2015
ABSTRACT
Molecules, 2015
Trapping of arynes with various nucleophiles provides a range of heteroatom-functionalized arene ... more Trapping of arynes with various nucleophiles provides a range of heteroatom-functionalized arene derivatives, but the corresponding reaction with water does not provide phenol derivatives. Silver trifluroacetate (AgO2CCF3) can nicely solve this problem. It was found that in typical organic solvent, AgO2CCF3 readily reacts with arynes to generate trifluoroacetoxy organosilver arene intermediate, which, upon treating with silica gel, provides phenolic products. This protocol can be extended to the synthesis of α-halofunctionalized phenol derivatives by simply adding NBS (N-bromosuccinimides) or NIS (N-iodosuccinimides) to the reaction along with silver trifluroacetate, which provided α-bromo or α-iodophenol derivatives in good yield. However, the similar reactions with NCS (N-chlorosuccinimides) afforded only the protonated product instead of the expected α-chlorophenols derivatives. Interestingly, substrates containing silyl substituents on 1,3-diynes resulted in α-halotrifluoroacetates rather than their hydrolyzed product. Additionally, trapping the same arynes with other oxygen-based nucleophiles containing silver counter cation, along with NXS (N-halosuccinimides), generated α-halooxyfunctionalized products.
Synthesis of Amathaspiramides by Aminocyanation of Enoates
Angewandte Chemie, 2015
Concise routes for the total and formal syntheses of the amathaspiramides were developed through ... more Concise routes for the total and formal syntheses of the amathaspiramides were developed through a formal [3+2] cycloaddition between lithium(trimethylsilyl)diazomethane and α,β-unsaturated esters. The effectiveness of this new cycloaddition for the construction of Δ(2) -pyrazolines containing a α-tert-alkylamino carbon center and subsequent facile protonolytic NN bond cleavage allows the synthesis of a key intermediate of the amathaspiramides and other α,α-disubstituted amino acid derivatives.
ChemInform Abstract: Dimerization Behavior of Substituted Bicyclo[3.1.0]hex-1-ene Derivatives
ChemInform, 2014
A novel bioluminescence-based method to investigate uptake of bile acids in living cells
American journal of physiology. Gastrointestinal and liver physiology, 2018
Bile acid transporters, including the ileal apical sodium-dependent bile acid transporter (ASBT) ... more Bile acid transporters, including the ileal apical sodium-dependent bile acid transporter (ASBT) and the hepatic sodium-taurocholate cotransporting polypeptide (NTCP), are crucial for the enterohepatic circulation of bile acids. Our objective was to develop a method for measuring bile acid transporter activity in real time to precisely evaluate rapid changes in their function. We designed a reporter system relying on a novel probe: cholic acid attached to luciferin via a disulfide-containing, self-immolating linker (CA-SS-Luc). Incubation of human embryonic kidney-293 cells coexpressing luciferase and ASBT with different concentrations of CA-SS-Luc (0.01-1 μM) resulted in bioluminescence with an intensity that was concentration- and time-dependent. The bioluminescence measured during incubation with 1 μM CA-SS-Luc was dependent on the levels of ASBT or NTCP expressed in the cells. Coincubation of CA-SS-Luc with natural bile acids enhanced the bioluminescence in a concentration-depen...
ChemInform Abstract: Total Synthesis of (3R,9R,10R)-Panaxytriol via Tandem Metathesis and Metallotropic [1,3]-Shift as a Key Step
ChemInform
ABSTRACT ChemInform is a weekly Abstracting Service, delivering concise information at a glance t... more ABSTRACT ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Synthesis of Novel Taxol Analogues and Evaluation of Their Biological Activities
ChemInform
ABSTRACT
Orthogonal lipid sensors identify transbilayer asymmetry of plasma membrane cholesterol
Nature chemical biology, Mar 26, 2016
Controlled distribution of lipids across various cell membranes is crucial for cell homeostasis a... more Controlled distribution of lipids across various cell membranes is crucial for cell homeostasis and regulation. We developed an imaging method that allows simultaneous in situ quantification of cholesterol in two leaflets of the plasma membrane (PM) using tunable orthogonal cholesterol sensors. Our imaging revealed marked transbilayer asymmetry of PM cholesterol (TAPMC) in various mammalian cells, with the concentration in the inner leaflet (IPM) being ∼12-fold lower than that in the outer leaflet (OPM). The asymmetry was maintained by active transport of cholesterol from IPM to OPM and its chemical retention at OPM. Furthermore, the increase in the IPM cholesterol level was triggered in a stimulus-specific manner, allowing cholesterol to serve as a signaling lipid. We found excellent correlation between the IPM cholesterol level and cellular Wnt signaling activity, suggesting that TAPMC and stimulus-induced PM cholesterol redistribution are crucial for tight regulation of cellular ...
Organic letters, Aug 22, 2016
A new benzannulation reaction with accompanied trifluoromethylthiolation is described. This benza... more A new benzannulation reaction with accompanied trifluoromethylthiolation is described. This benzannulation can generate a range of trifluoromethylthiolated benzolactams and benzolactones from 1,3,8-triynes and a stoichiometric amount of AgSCF3 at 90 °C through an initial Alder-ene reaction, 1,4-addition of AgSCF3, and a series of bond-reorganization processes that include double bond migration, 6π-electrocyclization, and a [1,3]-H shift. For certain substrates containing a triisopropylsilyl (TIPS) group, the final [1,3]-H shift-interrupted products, were obtained.
Initiation and Termination Mode of Enyne Cross-Metathesis and Metallotropic [1,3]-Shift Controlled by Remote Substituents
Journal of the American Chemical Society, Jul 7, 2010
The cross-metathesis of terminal alkyne and alkene using Ru-based Grubbs catalyst generally under... more The cross-metathesis of terminal alkyne and alkene using Ru-based Grubbs catalyst generally undergoes alpha-insertion. In this study, excellent control over alpha- and beta-insertion of ruthenium alkylidene into terminal alkynes has been achieved by using a substituent at a remote site from the reaction center. While the origin of this regioselectivity of insertion and metallotropic shift remains to be established, the trend indicates that the alpha-insertion with a concomitant metallotropic shift is favored with small substituents whereas the beta-insertion without a metallotropic shift is favored with bulky substituents such as tert-butyl and trialkyl silyl groups.
Organic Letters, Nov 1, 2001
A novel reaction between 1,3-dienes and selenium dioxide to give syn 1,2-and 1,4-diol cyclic sele... more A novel reaction between 1,3-dienes and selenium dioxide to give syn 1,2-and 1,4-diol cyclic selenites was studied in detail. This study indicates that an initial concerted [4 + 2] cycloaddition followed by a stereospecific carbon−selenium bond oxidation is involved in this unprecedented syn dihydroxy addition reaction mediated by selenium dioxide. The formation of a diol from an alkene is an important transformation in organic chemistry. 1 Usually, the syn addition of dihydroxy groups is achieved by OsO 4 , 2 RuO 4 , 3 and MnO 4 , 4 whereas anti addition is brought about by other oxides such as SeO 2 5 and WO 3. 6 In our investigations of the reaction between SeO 2 and 1,3-dienes, a novel reactivity profile of SeO 2 was observed, affording syn 1,2-and 1,4diols and selenophene. Treatment of diene 1, containing a carbonyl group at the C-1 position, with SeO 2 led to the formation of selenophene 2, whereas the analogous diene 3, containing a TBS-ether, yielded 1,4-diol cyclic selenite 4 and 1,2-diol cyclic selenite 5 (Scheme 1). Notably, the conversion of 3 to 4 involves an unprecedented direct oxidation of a C-Se bond to a CO bond, a transformation known to be difficult. 7 In this account, we elucidate the nature (1) (a) Haines, A. H. In ComprehensiVe Organic Synthesis; Trost, B.
J Am Chem Soc, 2005
Metathesis reactions O 0286 Cross and Ring-Closing Metathesis of 1,3-Diynes: Metallotropic [1,3]-... more Metathesis reactions O 0286 Cross and Ring-Closing Metathesis of 1,3-Diynes: Metallotropic [1,3]-Shift of Ruthenium Carbenes.-The cross metathesis of 1,3-diynes with alkenes proceeds with excellent regioselectivity. It does not depend on the substituents of the alkynes in contrast to the (E)/(Z)-selectivity. The ring-closing metathesis of ene-1,3-diynes provides products that contain fully conjugated 1,5-dien-3-yne moieties which are formed by ring closure and followed by facile metallotropic [1,3]-shift.-(KIM, M.; MILLER,
Overcoming catalytic bias
Nature, 2011
ChemInform Abstract: Regio‐ and Stereoselectivity in the Concatenated Enyne Cross Metathesis—Metallotropic [1,3]‐Shift of Terminal 1,3‐Diyne
Tetrahedron, Mar 11, 2014
Advances in the metallotropic [1,3]-shift of alkynyl carbenoids
Org Biomol Chem, 2007
Metal complexes of alkynyl carbenes undergo a [1,3]-bond shift known as a metallotropic shift. Si... more Metal complexes of alkynyl carbenes undergo a [1,3]-bond shift known as a metallotropic shift. Since the discovery of the metallotropic [1,3]-shift of Rh-carbenoid, many more alkynyl carbene complexes with Ti, Cr, Mn, Mo, Ru, W, Re, Pt, and Au have been discovered to show metallotropic shift behavior. This article briefly summarizes the [1,3]-bond shift of alkynyl carbenes and their metal complexes.
Journal of the American Chemical Society, Jul 1, 2009
The insertion of alkylidene carbenes into C-H bonds is a powerful synthetic tool for constructing... more The insertion of alkylidene carbenes into C-H bonds is a powerful synthetic tool for constructing stereochemically defined quaternary carbon centers. 1 Various forms of alkylidene carbene species, including 1-4, have been studied for their reactivity and employed in natural product syntheses. 2 In general, the C-H bonds become more reactive toward carbene insertion if an oxygen atom is directly connected to the reacting C-H bond. 3 However, how the oxygen atom activates the C-H bonds toward insertion or how much it contributes to the reactivity of the C-H bonds in 2 and 3 relative to that in 1 has not been elucidated.
Synthesis of the Carbocyclic Core of Massadine
Organic letters, Jan 6, 2015
The carbocyclic core of massadine has been synthesized relying on a stereoselective formal [3 + 2... more The carbocyclic core of massadine has been synthesized relying on a stereoselective formal [3 + 2] cycloaddition of lithiumtrimethylsilyldiazomethane with α,β-unsaturated esters to form a Δ(2)-pyrazoline moiety followed by facile N-N bond cleavage. A unique feature of the current approach is the direct installation of the tertiary α-amino center and a β-cyano group in a cis arrangement on the resulting cyclopentane framework via a previously developed formal aminocyanation protocol.
Oxidative Dimerization of Silylallenes via Activation of the Allenic C(sp(2))-H Bond Catalyzed by Copper(I) Chloride and N-Hydroxyphthalimide
Organic letters, Jan 2, 2015
Novel oxidative dimerization of silylallenes is described. Treatment of silylallenes with a catal... more Novel oxidative dimerization of silylallenes is described. Treatment of silylallenes with a catalytic amount of copper(I) chloride, a substoichiometric amount of N-hydroxyphthalamide, and a stoichiometric amount of a terminal oxidant diacetoxyiodobenzene afforded head-to-head dimers as the main products. Silyallenes containing a small ring afforded only dimers, whereas as the ring size increased 1,3-enynes became more favorable products. For silylallenes containing an acyclic substituent, dimer formation is a norm with exceptions where N-hydroxyphthalimide reacts at the propargylic center to generate the corresponding aminoxy ethers.
Mechanistic Understanding of the Divergent Cyclizations of o-Alkynylbenzaldehyde Acetals and Thioacetals Catalyzed by Metal Halides
Chemistry (Weinheim an der Bergstrasse, Germany), Jan 14, 2015
Invited for the cover of this issue are the groups of Yuanzhi Xia at Wenzhou University (P.R. Chi... more Invited for the cover of this issue are the groups of Yuanzhi Xia at Wenzhou University (P.R. China) and Daesung Lee at University of Illinois at Chicago (USA). The image depicts the mechanistic understanding of the regiodivergent cyclizations of- o-alkynylbenzaldehyde acetals and thioacetals catalyzed by metal halides. Read the full text of the article at 10.1002/chem.201502469.
ChemInform Abstract: Regio-and Stereoselective Metal-Catalyzed Reactions and Their Application to a Total Synthesis of (-)-Dactylolide
ChemInform
ChemInform Abstract: Benzannulation of Triynes to Generate Functionalized Arenes by Spontaneous Incorporation of Nucleophiles
ChemInform, 2015
ABSTRACT
Molecules, 2015
Trapping of arynes with various nucleophiles provides a range of heteroatom-functionalized arene ... more Trapping of arynes with various nucleophiles provides a range of heteroatom-functionalized arene derivatives, but the corresponding reaction with water does not provide phenol derivatives. Silver trifluroacetate (AgO2CCF3) can nicely solve this problem. It was found that in typical organic solvent, AgO2CCF3 readily reacts with arynes to generate trifluoroacetoxy organosilver arene intermediate, which, upon treating with silica gel, provides phenolic products. This protocol can be extended to the synthesis of α-halofunctionalized phenol derivatives by simply adding NBS (N-bromosuccinimides) or NIS (N-iodosuccinimides) to the reaction along with silver trifluroacetate, which provided α-bromo or α-iodophenol derivatives in good yield. However, the similar reactions with NCS (N-chlorosuccinimides) afforded only the protonated product instead of the expected α-chlorophenols derivatives. Interestingly, substrates containing silyl substituents on 1,3-diynes resulted in α-halotrifluoroacetates rather than their hydrolyzed product. Additionally, trapping the same arynes with other oxygen-based nucleophiles containing silver counter cation, along with NXS (N-halosuccinimides), generated α-halooxyfunctionalized products.
Synthesis of Amathaspiramides by Aminocyanation of Enoates
Angewandte Chemie, 2015
Concise routes for the total and formal syntheses of the amathaspiramides were developed through ... more Concise routes for the total and formal syntheses of the amathaspiramides were developed through a formal [3+2] cycloaddition between lithium(trimethylsilyl)diazomethane and α,β-unsaturated esters. The effectiveness of this new cycloaddition for the construction of Δ(2) -pyrazolines containing a α-tert-alkylamino carbon center and subsequent facile protonolytic NN bond cleavage allows the synthesis of a key intermediate of the amathaspiramides and other α,α-disubstituted amino acid derivatives.
ChemInform Abstract: Dimerization Behavior of Substituted Bicyclo[3.1.0]hex-1-ene Derivatives
ChemInform, 2014