Monofluoro-substituted azomethine ylides in fluorocarbene reactions with imines. Synthesis and transformations of monofluoroaziridines
作者:A. S. Konev、M. S. Novikov、A. F. Khlebnikov
DOI:10.1134/s1070428007020224
日期:2007.2
N-Arylmethylene and N-benzhydrylideneamines react with fluorocarbene yielding fluoro-substituted azomethine ylides that undergo 1,3-pi-cyclization into aziridines. Generation of fluoroylides in the presence of dipolarophiles (dimethyl maleate or dirnethyl acetylenedicarboxylate) led to the reaction of 1,3-dipolar cycloaddition resulting in substituted 2-pyrrolines or pyrroles. 2-Fluoroaziridines, products of N-alkyl-N-benzhydrylideneamines 1,3-pi-cyclization, in the presence of acid catalysts suffer isomerization into alpha-fluoroimines and 1,3-disubstituted indoles.
Regioselectivity of the 1,3-dipolar cycloaddition of fluorinated fluoren-9-iminium ylides to heteroelement-containing dipolarophiles: Experimental and quantum-chemical study
作者:M. S. Novikov、A. F. Khlebnikov、M. A. Egarmin、M. V. Shevchenko、V. A. Khlebnikov、R. R. Kostikov、D. Vidovic
DOI:10.1134/s1070428006120086
日期:2006.12
N-Substituted 9H-fluoren-9-imines react with difluorocarbene to give the corresponding iminium ylides whose further transformations in the absence of active dipolarophiles depend on the substituent at the nitrogen atom and reaction conditions. N-Ethyl-, N-benzyl-, and N-(2-phenylethyl)-9H-fluoren-9-imines are thus converted in low yield into the formal cyclodimerization products and/or 9H-fluorene-9-carboxamides. N-Methyl-substituted fluoreniminium ylide readily adds at the C=N bond of initial N-(9H-fluoren-9-ylidene)methanamine with formation of spiro-fused imidazolidine derivative; in the presence of fluorenone, acetaldehyde, or benzaldehyde, addition at the C=O group of the dipolarophile occurs to give the corresponding oxazolidine derivatives. The regioselectivity of the cycloaddition of iminium ylides having a fluorene fragment at a double carbon-heteroelement bond can be described by quantum-chemical calculations in terms of the density functional theory (DFT; local hard and soft acids and bases concept): the cycloaddition leads preferentially to the 2,2-difluoro-substituted adduct.
DAI, WEI;SRINIVASAN, RAJGOPAL;KATZENELLENBOGEN, JOHN A., J. ORG. CHEM., 54,(1989) N, C. 2204-2208
作者:DAI, WEI、SRINIVASAN, RAJGOPAL、KATZENELLENBOGEN, JOHN A.