ChemInform Abstract: Bimanes. Part 25. The Synthesis and Structures of Tricyclic Bimanes (. mu.-(Cn)-syn-(CH2, CH3 or Cl)B) (original) (raw)
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ChemInform, 1991
Alternative precursors to 1,4-acyl alkyl biradicals: cyclic N-acyl-1,1-diazenes
Journal of the American Chemical Society, 1984
George Gessert in providing illustrations of polyoxoanions appearing here and in our previous publication^.^ Supplementary Material Available: Detailed synthetic procedures for the synthesis of (B u~N)~H~S~~W~~N~~~~~ and (B U , N)~H S~~W ,~N~,~~, ; IR data and the ultracentrifugation solution molecular weight measurements on Si2W18Nb60778-and SiW9Nb30m7-(I pages). Ordering information is given on any current masthead page.
The Journal of Organic Chemistry, 1981
acetamide (7.5 g, 130 mmol, mp 82 "C) and the mixture heated at ca. 100 "C for 24 h. After cooling, the mixture is thoroughly triturated with CH2C12, in which CH3 CONHz is not very soluble, and chromatographed on silica gel, using EtOAc as eluant. The first compound eluted proved to be the diacetamido derivative 32, produced in 25% yield (35 mg) after crystallization. The second product was the bridged N-acetylimino compound (33): identical with a sample produced from the bridged imino compound and readily hydrolyzed to that compound. The bridged N-acetylimino compound was formed in this reaction in approximately 10-15% yield, but was the major product if the ratio of acetamide to dibromo compound were much smaller, e.g., 151. Hydrolysis of the diacetamido compound (20 mg) to the diamino derivative (34) was effected by 15% HCl at room temperature for 2 h. After neutralization of the acid with NaHCO,, the product was extracted with CH2C12, and 34 was obtained as a yellowish ~~ solid, 10 mg (70%). syn-(CH3CONHCH2,CH3)B (32): yellow needles (i-PrOH);
Synthesis and chemistry of a bicyclobutane-bridged .alpha.-diazoketone
The Journal of Organic Chemistry, 1980
The preparation and a number of reactions of the bicyclobutane-bridged a-diazo ketone 1 are reported. The 1,3-dipolar addition of 1 to activated unsaturated carbon-carbon bonds affords heterocyclics with an intact bicyclobutane ring system. Thii is exemplified by the reaction of 1 with enone 8 to give py-razoline 9 which provides upon photolytically or thermally induced extrusion of nitrogen the bis(bicyc1obutane)-substituted cyclopropane 16. Compound 16 isomerizes thermally to dihydrobenzofuran derivative 17, which is an example of a cyclopropyl ketone-dihydrofuran rearrangement. Also, some reactions of 1 involving loss of nitrogen were investigated. The transition-metal-catalyzed decomposition of 1 in methanol leads to mixtures of phenol 24 and 2,8cyclohexadienone 25. The AgC1C14-catalyzed decomposition of 1 in the presence of electron-rich alkenes affords aromatic adducts, arising from a (formal) 1,3-dipolar addition of the a-keto carbenoid species to the alkene, whereas the analogous reaction with Rh2(0A& furnish-47, resulting from (formal) dimerization of the a-keto carbenoid with incorporation of an oxygen atom. The reaction of 1 with tetrachloro-o-quinone leads to formation of 23 in which the bicyclobutane moiety has remained intact; on the other hand, treatment of 1 with o-dihydroxybenzene provides a mixture of the rearranged adducts 49 and 51. Finally, the preparation and some properties of bis(tosy1hydrazone) 4 are described.
Synthesis of o,m-cymene-cored biaryls through a carbanion-induced ring transformation strategy
Tetrahedron Letters, 2006
Aromatic compounds derived from two or more 'isoprene units' are the core structures found in several natural products of biological importance. Among them, cymene derivatives are of particular interest due to the unique structural and biological properties associated with them. In this letter, we describe an expeditious synthesis of cymene-cored unsymmetrical biaryls functionalized with donor and acceptor substituents prepared in excellent yields by the carbanion-induced ring transformation of 2H-pyran-2-ones with ketones.
The Journal of Organic Chemistry, 2005
We observed a nucleophilic attack by the ene-amino carbon of 3-dimethylaminopropenoates at the terminal carbon of the azo-ene system of 1,2-diaza-1,3-butadienes. In tetrahydrofuran at 65°C, this attack produced 1-aminopyrrolines with a high degree of cis-stereoselectivity by means of an unusual zwitterionic adduct intermediate followed by intramolecular ring closure. In toluene under reflux, 1-aminopyrrolines produced oxazoline-fused 1-aminopyrrolines. Oxazoline-fused 1-aminopyrrolines were directly obtained by reaction of 1,2-diaza-1,3-butadienes with 3-dimethylaminopropenoates in toluene under reflux. The ring opening of oxazoline-fused 1-aminopyrrolines in acidic or basic media provides highly substituted 1-aminopyrroles. 5-Unsubstituted 1-aminopyrrole derivatives were obtained from 1-aminopyrrolines under basic conditions by loss of dimethylamino and ester groups. We discuss the plausible mechanisms of the ring closure and opening. (1) For the synthesis and application of this and related compounds, see: (a) Hvala, A.; Simonic, I.; Stanovnik, B.; Svete, J.; Tisler, M.; Zorz, L. Heterocycles 1988, 27, 903. (b) Č adež, Z.; Stanovnik, B.; Svete, J.; Tišler, M. (2) For the synthesis and application of this and related compounds, see: (a) Sommer, S. Tetrahedron Lett. 1977, 18, 117. (b) Attanasi, O. A.; Filippone, P.; Mei, A.; Santeusanio, S. Synthesis 1984, 671. (c) Attanasi, O. A.; Filippone, P.; Mei, A.; Santeusanio, S. Synthesis 1984, 873. (d) Attanasi, O. A.; De Crescentini, L.; Filippone, P.; Mantellini, F.; Santeusanio, S. Arkivoc 2002, xi, 274. (e) Attanasi, O. A.; De Crescentini, L.; Favi, G.; Filippone, P.; Giorgi, G.; Mantellini, F.; Santeusanio, S.
New bicyclic system. N,N'-Diaryl-2,5-diaza-3,6-dioxobicyclo[2.2.2]octanes
Journal of Organic Chemistry, 1971
The reaction of a,a'-dibromoadipic acid bisarylamides with anhydrous potassium fluoride gives a new bicyclic system, N,N'-diaryl-2,5-diaza-3,6-dioxobicyclo[2.2.2] octanes, together with the bisarylamides of ala'-difluoroadipic and muconic acid. The chemical and physical properties of the bicyclic system are reported. During our investigation of the reaction of amides of a-bromo acids with potassium fluoridell it has been observed that, ala'-dibromoadipic acid dianilideis transformed in this reaction into a mixture of three substances: ala'-difluoroadipic acid dianilide (IIIa), 6 4.66 ppm from 5 to 1.3 cps.
Stille cross coupling protocols were utilized for the synthesis of 3-(biaryl)-8-oxabicyclo[3.2.1]oct-2-ene-2-carboxylic acid methyl esters, which furnished products in high yields where in some cases Suzuki coupling under the conditions utilized provided complex reaction mixture. Samarium iodide reduction of the resulting coupling products produced both of the 2b-carbomethoxy-3-biaryl-8-oxabicyclo[3.2.1]octane diastereomers and the 2a-carbomethoxy-3-biaryl-8-oxabicyclo[3.2.1]octane diastereomers. Among the series synthesized, the benzothiophene substituted compounds demonstrated significant binding profiles of inhibition of WIN 35,438 with 177-fold selectivity for DAT versus SERT.
Diazocinones: Synthesis and Conformational Analysis
Journal of Organic Chemistry, 2006
Tetrazines (prepared from aryl nitriles) condense with isoxazolylcyclobutanones (prepared from 3-benzenesulfonyl-3-vinylcyclobutanol) in methanolic KOH to give conformationally restricted 6-isoxazol-5-yl-6,7-dihydro-5H-[1,2]diazocin-4-ones. The solution 1 H NMR spectra of dihydrodiazocinone 1a with phenyl moieties at C3 and C8 reveal two conformations of the eight-membered heterocycle that are non-interconverting on the NMR time scale at ambient temperature. The kinetics of the conversion process, followed by 1 H NMR between 21 and 70°C in DMSO solution, yield an activation energy of ∼21 kcal/mol relative to the kinetic conformer and show an equilibrated ratio of ∼5:1 of the thermodynamic to the kinetic conformers. The electronic structure calculations on a model dihydrodiazocinone predict geometries for the two conformations. One of these geometries agrees with the X-ray crystallographic analysis of the thermodynamic conformation of 1a.