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A new method was designed for the synthesis of enantioenriched indanones by asymmetric carbonyl-ene/intramolecular Heck cyclization from racemic silyloxyallenes. Short reaction times and high yields of the modular procedure is demonstrated by production of highly substituted indenes and indanones with excellent chirality transfer from the optically active carbinols.

The enantioselective synthesis of [alpha],[ alpha]-disubstituted cyclopentenes by an intramolecular aldol reaction of achiral tricarbonyl compounds catalyzed by chiral N-heterocyclic carbenes is presented.

An approach to assessing tertiary [beta]-hydroxy amides by the addition of an amide enolate to an acylsilane is reported, which utilizes a 1.2-silyl group migration from carbon to oxygen to form [beta]-silyloxy homonates. It is observed that amide enolates strongly favor C-alkylation of the homoenolate over O-alkylation or the formation of alkoxy cyclopropanes.

A study shows that silyloxyallenes generated from acylsilanes undergo scandium (III)-catalyzed [alpha]-acylvinyl additions to a variety of aldehydes. Results reveal that a wide range of [Beta]-substitution on the alleric is accommodated with excellent yields and a high degree of control over the new alkene geometry, and the carbinol stereocenter of the resulting unsaturated ketone products can be controlled by a chiral catalyst.

The highly diastereo- and enantioselective combination of [alpha],[beta]-unsaturated aldehydes with nitrones catalyzed by N-heterocyclic carbenes to yield [gamma]-amino esters upon the addition of an alcohol is described. N-heterocyclic carbene catalysis is shown as a powerful method that has provided new directions for the synthesis through innovative bond construction.

The first direct nucleophilic acylation of nitroalkenes to produce beta-nitro ketones by the combination of a fluoride source with silylated thiazolium carbinols are described. The distinct fluoride-activated acyl anion strategy is divergent from the typical combinations of heteroazolium salts and bases and thus allows for the use of reactive nitroalkenes as substrates.

The article describes the enantioselective synthesis of αα-disubstituted cyclopentenes by an intramolecular aldol reaction of achiral tricarbonyl compounds catalyzed by chiral N-heterocyclic carbenes. According to the authors, the process combines an enantioselective aldol reaction with a decarboxylation of a β-lactone intermediate to afford functionalized carbocycles containing a quaternary carbon stereocenter.

alpha-Hydroxypropargylsilanes undergo rearrangement to form reactive lithium allenolates. The resulting alpha-acylvinyl anion equivalents undergo highly selective additions to N-tert-butanesulfinyl imines generating beta-substituted aza-MBH-type products. High yields are achieved for a wide range of alpha-hydroxypropargylsilanes as well as for a diverse selection of imines. The reactions proceed with good to excellent diastereoselectivity and regioselectivity (8-20:1 major/ Sigma minor) favoring the Z-isomer of the alkene.

Silyloxyallenes serve as highly useful alpha-acylvinyl anion equivalents. These latent allenolates undergo conjugate additions to alkylidene malonates in the presence of 10 mol % Sc(OTf) 3. The reaction delivers intermolecular Rauhut-Currier products in excellent yields and regioselectivities for a wide scope of substrates. Notably, the formal cross-coupling of two different alpha,beta-unsaturated carbonyl compounds (a cross Rauhut-Currier reaction) is achieved. Preliminary investigations have demonstrated good levels of enantioselectivity for the addition of a racemic silyloxyallene with a chiral Lewis acid.

Highly substituted alpha,beta-unsaturated ketones are prepared by the N-heterocyclic carbene-initiated addition of alpha-hydroxypropargylsilanes to aldehydes. This strategy serves as a highly efficient alternative to the standard Morita-Baylis-Hillman (MBH) approaches for these types of compounds. In contrast to the MBH reaction, different substitution in the beta-position of the product (R1) can be accommodated in moderate to excellent yields with a high degree of control over the resulting alkene.