protonation of the reactive intermediates generated in the raction between dalkyl acetylenedicarboxylates and triphenylphosphine by isonitrosoacetophenone leads to vinyltriphenylphosphonium salts, which undergo intramolecular wittig reaction to produce dalkyl 4-phenyl-n-hydroxypyrrole-2,3-dicarboxylates in moderate yields.

An efficient synthesis of some novel coumarin derivatives via 1, 4- Michael addition of indole to coumarin chalcones catalyzed by cellulose sulphonic acid (CSA) under solvent free conditions is described. The corresponding Michael addition products were obtained in good to excellent yield. The synthesized compounds were screened for their antibacterial activity against E. coli, S. aureus and an...

An efficient synthesis of some novel coumarin derivatives via 1, 4- Michael addition of indole to coumarin chalcones catalyzed by cellulose sulphonic acid (CSA) under solvent free conditions is described. The corresponding Michael addition products were obtained in good to excellent yield. The synthesized compounds were screened for their antibacterial activity against E. coli, S. aureus and an...

Enzymes can substantially increase the probability of a reaction by exploiting binding energy to preorganize their substrates into reactive conformations. Similar effects are likely to be important in a wide variety of designed catalysts, including catalytic antibodies. Transferred nuclear Overhauser effects have been used here to investigate how an antibody possessing chorismate mutase activit...

The polarity reversible nature of azomethine imines as the crucial transformation enables the tandem Michael addition/imine isomerization/[3+2] cycloaddition to proceed under mild, transition-metal-free conditions to form cyclohepta[b]pyrroles in a single operation starting from readily available acyclic precursors with a broad substrate scope.

The racemic modifications of title natural products 1 and 2 have been synthesised for the first time. The key step was the Au(i)-catalysed conversion of the furanyl-substituted ynone 13 into the annulated furan 14.

Continuing a line of research opened up by Grigni and Sipser in 4] and further pursued in 10], we show that a wide variety of equivalent characterizations of P still remain equivalent when restricted to be positive. All these restrictions thus deene the same class posP, a proper subclass of monP, the class of monotone problems in P. We also exhibit complete problems for posP under very weak red...