Addition of Organometallic Reagents to Aldehydes

To account for the observed diastereoselectivity, a modified Felkin-Anh model has been proposed [18]. In analogy to the classical Felkin-Anh model, originally developed for the addition of organometallic reagents to aldehydes possessing a... 

In our group the diastereoselective 1,2-addition of organometallic reagents to aldehyde SAMP hydrazones was employed in the synthesis of several alkaloids and we have now extended our method to the efficient asymmetric synthesis of the poison-dart-frog indolizidine alkaloids 2091 and 223J and their enantiomers via a common late-stage intermediate amino nitrile (5R,8R,8aS)-63 [45]. This amino nitrile chemistry had previously been used by Polniaszek and Belmont in the first enantioselective total syntheses of 5,8-disubstituted indolizidine alkaloids [46]. They were able to prepare the indolizidines 205A (65) from 64 in one or two steps (Scheme 1.2.15). 

Addition of organometallic reagent to aldehyde preparation of secondary alcohols... 

Highly enantioselective asymmetric syntheses of pyridyl by addition of organometallic reagents to aldehydes, autocatalysis by the formed chiral adduct 04YGK673. 

In contrast to the asymmetric reduction of carbonyl compounds where fairly high e.e. had been realized, the asymmetric addition of organometallic reagents to aldehydes in a chiral solvent, or by using chiral ligands such as (—)-spartein and (—)-N-methylephedrine to afford optically active alcohols had met with only... 

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