Phase-transfer catalysis conjugate additions with

Michael-aldol reaction as an alternative to the Morita-Baylis-Hillman reaction 14 recent results in conjugate addition of nitroalkanes to electron-poor alkenes 15 asymmetric cyclopropanation of chiral (l-phosphoryl)vinyl sulfoxides 16 synthetic methodology using tertiary phosphines as nucleophilic catalysts in combination with allenoates or 2-alkynoates 17 recent advances in the transition metal-catalysed asymmetric hydrosilylation of ketones, imines, and electrophilic C=C bonds 18 Michael additions catalysed by transition metals and lanthanide species 19 recent progress in asymmetric organocatalysis, including the aldol reaction, Mannich reaction, Michael addition, cycloadditions, allylation, epoxidation, and phase-transfer catalysis 20 and nucleophilic phosphine organocatalysis.21... 

Tanikaga and coworkers have reported the addition of nitroalkane anions to a-halo-a,P-unsaturated sulfoxides [72]. Further development of this work led to the use of nitroalkanes as alkyl group equivalents in conjugate addition to a,P-unsaturated sulfoxides [73-75]. Primary or secondary nitroalkanes such as 2-nitropropane (77), with DBU as a non-nucleophilic base, add to a,P-unsaturated sulfoxides including phenyl vinyl sulfoxide (26) to give products such as (78), which can be denitrated to yield (79) (Scheme 5.25). The Michael addition of nitroalkanes, and of diethyl N-acetylaminomalonate, to racemic phenyl vinyl sulfoxide using solid-liquid phase-transfer catalysis in the absence of solvent has also been accomplished [76]. 

Chiral ion pairs (B, Fig. 2.2) can be formed by deprotonation of the pronucleophile with a chiral Brpnsted base or employing an achiral base and a chiral phase-transfer catalyst. Chiral phase-transfer catalysis (PTC) [8] illustrates how ion pairing interactions can be used to carry out the enantioface discrimination in conjugate addition reactions. In both cases, the chiral cation is responsible for... 

Enantioselective phase-transfer catalysis (PTC) has been extensively applied for the alkylation, epoxidation, conjugate addition and related process, with the use of chiral ammonium salts being the typical transfer agent [293]. However, the related aldol... 

Cyclopropanecarboxylic esters have been prepared, in 75—86 % yield, by intramolecular alkylation of 4-chloroalkyl esters, using phase-transfer catalysis. Monoalkylation of nitro-alkenes by acrylic esters occurs in a controlled manner if a two-phase system is used, to give products of Michael addition in 45—65 % yield for five examples. An interesting variant on this reaction involves the generation of the a-nitro-carbanion by conjugate reduction of a nitroalkene with sodium borohydride followed by its conjugate addition to methyl acrylate yields of 62—95% are reported for five cases (Scheme 39). ... 

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