Shawn Hitchcock | Illinois State University (original) (raw)
Papers by Shawn Hitchcock
Encyclopedia of Reagents for Organic Synthesis, Oct 15, 2005
ChemInform, Jul 31, 2007
A series of oxazolidines have been prepared by reaction of either (1R,2S)-ephedrine or (1S,2S)-ps... more A series of oxazolidines have been prepared by reaction of either (1R,2S)-ephedrine or (1S,2S)-pseudoephedrine with salicylaldehyde derivatives. The resultant oxazolidines were used as catalytic ligands in the addition of diethylzinc to a variety of aromatic and aliphatic aldehydes. It was determined that the (1R,2S)-ephedrine based oxazolidine derivative 9 gave the highest enantioselectivities.
ChemInform, May 5, 2009
www.cheminform.wiley-vch.de Enantioselective syntheses O 0031 Divergent Enantioselective Pathways... more www.cheminform.wiley-vch.de Enantioselective syntheses O 0031 Divergent Enantioselective Pathways in the Catalytic Asymmetric Addition of Diethylzinc to Aldehydes in the Presence and Absence of Titanium Tetraisopropoxide.-Enantiodivergent addition of ZnEt2 to aldehydes, depending on the presence or absence of Ti(O-iPr)4, is achieved using hydrobenzoin as the catalytic ligand. A similar reversal of enantioselectivity is not observed when hydrobenzoin is replaced by N-methylephedrin.-(DEAN, M. A.
ChemInform, Feb 17, 2004
Other 6-membered heterocycles Other 6-membered heterocycles R 0670 Oxadiazinones as Chiral Auxili... more Other 6-membered heterocycles Other 6-membered heterocycles R 0670 Oxadiazinones as Chiral Auxiliaries: Diastereoselective Aldol Addition Reactions of N 3-Glycolyl-3,4,5,6-tetrahydro-2H-1,3,4-oxadiazin-2-ones.-Asymmetric aldol addition of aromatic aldehydes to a variety of enantiopure ephedrine-derived N 3-glycolyloxadiazinones (III) is presented. The reaction provides access to the non-Evans syn-aldol adducts in moderate to high yields and diastereoselectivities. In general, better results are obtained for the aryloxyacetyl-substituted oxadiazinones (IIIa) and (IIIb), while the benzyloxyacetyl analogue (IIId) is completely unreactive under the reaction conditions.-(HOOVER,
Tetrahedron-asymmetry, Nov 1, 2008
The stereochemical outcome of the asymmetric addition of diethylzinc to aldehydes catalyzed by (R... more The stereochemical outcome of the asymmetric addition of diethylzinc to aldehydes catalyzed by (R,R)-hydrobenzoin can be influenced by the absence or presence of Ti(O-iPr)4. The enantiomeric ratios obtained in the absence of Ti(O-iPr)4 favor the (S)-enantiomer, whereas the ratios obtained from the use of Ti(O-iPr)4 favor the formation of the (R)-enantiomer. The formation of the opposite enantiomers is attributed to
ChemInform, Aug 3, 2004
Other 6-membered heterocycles Other 6-membered heterocycles R 0670 Synthesis of 3,4,5,6-Tetrahydr... more Other 6-membered heterocycles Other 6-membered heterocycles R 0670 Synthesis of 3,4,5,6-Tetrahydro-2H-1,3,4-oxadiazin-2-ones Employing a Metal Hydride and Diethyl Carbonate: An Alternative Cyclization Method over 1,1'-Carbonyldiimidazole.-A series of the title tetrahydrooxadiazinones [cf. (III) and (IX)] are synthesized via cyclization of β-hydrazino alcohols derived from amino acids with diethyl carbonate (II) in the presence of a metal hydride. The use of diethyl carbonate (II) in conjunction with a metal hydride proves to be just as effective as 1,1'-carbonyldiimidazole.
ChemInform, May 18, 2010
For Abstract see ChemInform Abstract in Full Text.
ChemInform, Mar 11, 2008
Isoquinoline derivatives R 0420 Preparation of Some Derivatives of N-tert-Butyldecahydro-3-isoqui... more Isoquinoline derivatives R 0420 Preparation of Some Derivatives of N-tert-Butyldecahydro-3-isoquinoline Carboxamide.-The N-alkylation of title compound (I), a key structural fragment present in a variety of HIV protease inhibitors, is studied. Attempts to synthesize the aldehyde (IV) via Swern oxidation of (IIIa) are not successful; (IV) is rather obtained from the diacetal (IIIb). The deprotection of the latter succeeds with BBr3 under mild conditions whereas other known methods fail.-(CASPER, D.
ChemInform, Jun 13, 2010
Reductive Dehydroxy Coupling of 2-(Hydroxymethyl)indenes to Prepare Ethano-Bridged Bis(2-indenyl)... more Reductive Dehydroxy Coupling of 2-(Hydroxymethyl)indenes to Prepare Ethano-Bridged Bis(2-indenyl) ansa-Titanocenes.-Several novel bis(2-indenyl)ethane derivatives (II) are prepared by Ti-mediated reductive coupling of 2-(hydroxymethyl)indenes (I). The yield of the regioisomeric α-coupling by-products (III) can be decreased by introduction of a substituent into position C-3 or C-1 of the indene derivative (I). Treatment of the dianions of (II) with TiCl 3 (thf) 3 under literature conditions provides novel ansa-titanocenes as mixtures of rac/meso-diastereomers.-(PALANDOKEN,
Acta Crystallographica Section E-structure Reports Online, Nov 27, 2010
ChemInform, Sep 30, 2010
A range of ephedrine-like ligands is prepared varying mainly the N-benzyl moiety of original ephe... more A range of ephedrine-like ligands is prepared varying mainly the N-benzyl moiety of original ephedrine.
Tetrahedron-asymmetry, Nov 1, 2016
Using a single chiral scaffold, (1R,2S)-norephedrine, a series of monophosphine ligands have been... more Using a single chiral scaffold, (1R,2S)-norephedrine, a series of monophosphine ligands have been prepared. The ligands prepared, b-acyloxy-(o-diphenylphosphino)amides and b-amido-(o-diphenylphosphino)esters, give rise to enantiomerically divergent products in the Tsuji-Trost asymmetric allylic reaction. The phosphinoamides afforded the best enantioselectivities and favored the (S)-enantiomer of the product. In contrast the phosphinoesters afforded lower enantioselectivities and favored the (R)enantiomer. A mechanistic rationale for this observation is proposed.
Organic preparations and procedures international, Feb 1, 1992
Page 1. ORGANIC PREPARATIONS AND PROCEDURES IN&quot;., 24 (l), 39-43 (1992) AN IMPROVED P... more Page 1. ORGANIC PREPARATIONS AND PROCEDURES IN&quot;., 24 (l), 39-43 (1992) AN IMPROVED PROCEDURE FOR THE PREPARATION AND RESOLUTION OF DL-2,3-DIMETHYLSUCCINIC ACID Scott C. Sutton, Michael H. Nand and Shawn R. Hitchcock ...
Organic Letters, Sep 17, 2002
ChemInform, Mar 6, 2001
X-Ray Crystallographic Analysis and Photochemical Reaction of Asymmetrically Substituted α,β-Unsa... more X-Ray Crystallographic Analysis and Photochemical Reaction of Asymmetrically Substituted α,β-Unsaturated Thioamides-[(I) in benzene and the solid state leading to (II) and/or (III) and (IV)].
![Research paper thumbnail of Conformational Studies of <i>N</i><sub>3</sub>-Substituted [1,3,4]-Oxadiazinan-2-ones](https://attachments.academia-assets.com/111505302/thumbnails/1.jpg)
](Journal of Organic Chemistry, Nov 19, 2002
Pseudoephedrine-based [1,3,4]-oxadiazinan-2-ones acylated at the N 3-position with either acetyl ... more Pseudoephedrine-based [1,3,4]-oxadiazinan-2-ones acylated at the N 3-position with either acetyl (2a), propionyl (2b), or phenylacetyl (2c) substituents are known to undergo conformational changes that are observable by 13 C NMR spectroscopy. The conformational properties of new [1,3,4]oxadiazinan-2-one derivatives 2d-k are examined by X-ray crystallography and variabletemperature 13 C NMR spectroscopy and further evaluated by semiempirical AM1 calculations. The collected data reveal that the conformational changes of the overall ring system are dependent upon the stereoelectronic factors of the N 3-substituent.
ChemInform, Aug 23, 2010
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 100 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.
![Research paper thumbnail of (6<i>S</i>)-2,4-Di-<i>tert</i>-butyl-6-[(4<i>S</i>,5<i>R</i>)-3-isopropyl-4-methyl-5-phenyloxazolidin-2-yl]phenol](https://attachments.academia-assets.com/111505289/thumbnails/1.jpg)
](Acta Crystallographica Section E-structure Reports Online, Mar 24, 2010
ChemInform, Dec 9, 2010
The Ephedra‐based oxadiazines (IV), (VII) and (VIII) are synthesized as potential tools for condu... more The Ephedra‐based oxadiazines (IV), (VII) and (VIII) are synthesized as potential tools for conducting asymmetric syntheses via intramolecular chiral relay.
Encyclopedia of Reagents for Organic Synthesis, Oct 15, 2005
ChemInform, Jul 31, 2007
A series of oxazolidines have been prepared by reaction of either (1R,2S)-ephedrine or (1S,2S)-ps... more A series of oxazolidines have been prepared by reaction of either (1R,2S)-ephedrine or (1S,2S)-pseudoephedrine with salicylaldehyde derivatives. The resultant oxazolidines were used as catalytic ligands in the addition of diethylzinc to a variety of aromatic and aliphatic aldehydes. It was determined that the (1R,2S)-ephedrine based oxazolidine derivative 9 gave the highest enantioselectivities.
ChemInform, May 5, 2009
www.cheminform.wiley-vch.de Enantioselective syntheses O 0031 Divergent Enantioselective Pathways... more www.cheminform.wiley-vch.de Enantioselective syntheses O 0031 Divergent Enantioselective Pathways in the Catalytic Asymmetric Addition of Diethylzinc to Aldehydes in the Presence and Absence of Titanium Tetraisopropoxide.-Enantiodivergent addition of ZnEt2 to aldehydes, depending on the presence or absence of Ti(O-iPr)4, is achieved using hydrobenzoin as the catalytic ligand. A similar reversal of enantioselectivity is not observed when hydrobenzoin is replaced by N-methylephedrin.-(DEAN, M. A.
ChemInform, Feb 17, 2004
Other 6-membered heterocycles Other 6-membered heterocycles R 0670 Oxadiazinones as Chiral Auxili... more Other 6-membered heterocycles Other 6-membered heterocycles R 0670 Oxadiazinones as Chiral Auxiliaries: Diastereoselective Aldol Addition Reactions of N 3-Glycolyl-3,4,5,6-tetrahydro-2H-1,3,4-oxadiazin-2-ones.-Asymmetric aldol addition of aromatic aldehydes to a variety of enantiopure ephedrine-derived N 3-glycolyloxadiazinones (III) is presented. The reaction provides access to the non-Evans syn-aldol adducts in moderate to high yields and diastereoselectivities. In general, better results are obtained for the aryloxyacetyl-substituted oxadiazinones (IIIa) and (IIIb), while the benzyloxyacetyl analogue (IIId) is completely unreactive under the reaction conditions.-(HOOVER,
Tetrahedron-asymmetry, Nov 1, 2008
The stereochemical outcome of the asymmetric addition of diethylzinc to aldehydes catalyzed by (R... more The stereochemical outcome of the asymmetric addition of diethylzinc to aldehydes catalyzed by (R,R)-hydrobenzoin can be influenced by the absence or presence of Ti(O-iPr)4. The enantiomeric ratios obtained in the absence of Ti(O-iPr)4 favor the (S)-enantiomer, whereas the ratios obtained from the use of Ti(O-iPr)4 favor the formation of the (R)-enantiomer. The formation of the opposite enantiomers is attributed to
ChemInform, Aug 3, 2004
Other 6-membered heterocycles Other 6-membered heterocycles R 0670 Synthesis of 3,4,5,6-Tetrahydr... more Other 6-membered heterocycles Other 6-membered heterocycles R 0670 Synthesis of 3,4,5,6-Tetrahydro-2H-1,3,4-oxadiazin-2-ones Employing a Metal Hydride and Diethyl Carbonate: An Alternative Cyclization Method over 1,1'-Carbonyldiimidazole.-A series of the title tetrahydrooxadiazinones [cf. (III) and (IX)] are synthesized via cyclization of β-hydrazino alcohols derived from amino acids with diethyl carbonate (II) in the presence of a metal hydride. The use of diethyl carbonate (II) in conjunction with a metal hydride proves to be just as effective as 1,1'-carbonyldiimidazole.
ChemInform, May 18, 2010
For Abstract see ChemInform Abstract in Full Text.
ChemInform, Mar 11, 2008
Isoquinoline derivatives R 0420 Preparation of Some Derivatives of N-tert-Butyldecahydro-3-isoqui... more Isoquinoline derivatives R 0420 Preparation of Some Derivatives of N-tert-Butyldecahydro-3-isoquinoline Carboxamide.-The N-alkylation of title compound (I), a key structural fragment present in a variety of HIV protease inhibitors, is studied. Attempts to synthesize the aldehyde (IV) via Swern oxidation of (IIIa) are not successful; (IV) is rather obtained from the diacetal (IIIb). The deprotection of the latter succeeds with BBr3 under mild conditions whereas other known methods fail.-(CASPER, D.
ChemInform, Jun 13, 2010
Reductive Dehydroxy Coupling of 2-(Hydroxymethyl)indenes to Prepare Ethano-Bridged Bis(2-indenyl)... more Reductive Dehydroxy Coupling of 2-(Hydroxymethyl)indenes to Prepare Ethano-Bridged Bis(2-indenyl) ansa-Titanocenes.-Several novel bis(2-indenyl)ethane derivatives (II) are prepared by Ti-mediated reductive coupling of 2-(hydroxymethyl)indenes (I). The yield of the regioisomeric α-coupling by-products (III) can be decreased by introduction of a substituent into position C-3 or C-1 of the indene derivative (I). Treatment of the dianions of (II) with TiCl 3 (thf) 3 under literature conditions provides novel ansa-titanocenes as mixtures of rac/meso-diastereomers.-(PALANDOKEN,
Acta Crystallographica Section E-structure Reports Online, Nov 27, 2010
ChemInform, Sep 30, 2010
A range of ephedrine-like ligands is prepared varying mainly the N-benzyl moiety of original ephe... more A range of ephedrine-like ligands is prepared varying mainly the N-benzyl moiety of original ephedrine.
Tetrahedron-asymmetry, Nov 1, 2016
Using a single chiral scaffold, (1R,2S)-norephedrine, a series of monophosphine ligands have been... more Using a single chiral scaffold, (1R,2S)-norephedrine, a series of monophosphine ligands have been prepared. The ligands prepared, b-acyloxy-(o-diphenylphosphino)amides and b-amido-(o-diphenylphosphino)esters, give rise to enantiomerically divergent products in the Tsuji-Trost asymmetric allylic reaction. The phosphinoamides afforded the best enantioselectivities and favored the (S)-enantiomer of the product. In contrast the phosphinoesters afforded lower enantioselectivities and favored the (R)enantiomer. A mechanistic rationale for this observation is proposed.
Organic preparations and procedures international, Feb 1, 1992
Page 1. ORGANIC PREPARATIONS AND PROCEDURES IN&quot;., 24 (l), 39-43 (1992) AN IMPROVED P... more Page 1. ORGANIC PREPARATIONS AND PROCEDURES IN&quot;., 24 (l), 39-43 (1992) AN IMPROVED PROCEDURE FOR THE PREPARATION AND RESOLUTION OF DL-2,3-DIMETHYLSUCCINIC ACID Scott C. Sutton, Michael H. Nand and Shawn R. Hitchcock ...
Organic Letters, Sep 17, 2002
ChemInform, Mar 6, 2001
X-Ray Crystallographic Analysis and Photochemical Reaction of Asymmetrically Substituted α,β-Unsa... more X-Ray Crystallographic Analysis and Photochemical Reaction of Asymmetrically Substituted α,β-Unsaturated Thioamides-[(I) in benzene and the solid state leading to (II) and/or (III) and (IV)].
Journal of Organic Chemistry, Nov 19, 2002
Pseudoephedrine-based [1,3,4]-oxadiazinan-2-ones acylated at the N 3-position with either acetyl ... more Pseudoephedrine-based [1,3,4]-oxadiazinan-2-ones acylated at the N 3-position with either acetyl (2a), propionyl (2b), or phenylacetyl (2c) substituents are known to undergo conformational changes that are observable by 13 C NMR spectroscopy. The conformational properties of new [1,3,4]oxadiazinan-2-one derivatives 2d-k are examined by X-ray crystallography and variabletemperature 13 C NMR spectroscopy and further evaluated by semiempirical AM1 calculations. The collected data reveal that the conformational changes of the overall ring system are dependent upon the stereoelectronic factors of the N 3-substituent.
ChemInform, Aug 23, 2010
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 100 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.
Acta Crystallographica Section E-structure Reports Online, Mar 24, 2010
ChemInform, Dec 9, 2010
The Ephedra‐based oxadiazines (IV), (VII) and (VIII) are synthesized as potential tools for condu... more The Ephedra‐based oxadiazines (IV), (VII) and (VIII) are synthesized as potential tools for conducting asymmetric syntheses via intramolecular chiral relay.