Organocatalytic Asymmetric Cycloaddition Reaction of Ketenes

Benzene construction via organocatalytic formal [3+3] cycloaddition reaction.

The benzene unit, in its substituted forms, is a most common scaffold in natural products, bioactive molecules and polymer materials. Nearly 80% of the 200 best selling small molecule drugs contain at least one benzene moiety. Not surprisingly, the synthesis of substituted benzenes receives constant attentions. At present, the dominant methods use pre-existing benzene framework to install subst...

REACTION OF QUINONEIMINES WITH KETENES

The reactivity of quinoneimines towards ketene and diphenylketene was examined. N-Phenylbenzoquinoneirnines (I), (2) and also N-phenylnaphthoquinoneimine react with ketene to give the spiro-adducts (5), (7) and (1 1) respectively. These adducts were stable even after prolonged heating in high boiling solvent. Reaction of the above imines with diphenylketene also afforded 13- lactam spiro-a...

Organocatalytic asymmetric formal [3+2] cycloaddition reaction of isocyanoesters to nitroolefins leading to highly optically active dihydropyrroles.

The asymmetric synthesis of CF3-containing spiro[pyrrolidin-3,2'-oxindole] through the organocatalytic 1,3-dipolar cycloaddition reaction.

A new strategy for the construction of optically active 5'-CF3 spiro[pyrrolidin-3,2'-oxindole] was described. A series of unprecedented 1,3-dipoles were obtained by condensation of CF3CH2NH2 with isatins. The 1,3-dipolar cycloaddition reactions of these ketimines with enals gave the products bearing four contiguous stereogenic centers in excellent yields, diastereoselectivities and enantioselec...

Organocatalytic asymmetric "anti-Michael" reaction of beta-ketoesters.

The first organocatalytic "anti-Michael" reaction of cyclic-beta-ketoesters to unsaturated double bonds is described in a highly asymmetric version leading to the synthesis of alpha,alpha'-disubstituted branched double bonds as optically active Baylis-Hillman-like adducts.