Influence of β-Substituents in Aldol Reactions of Boron Enolates of β-Alkoxy Methylketones

Catalytic strategies towards 1,3-polyol synthesis by enantioselective cascades creating multiple alcohol functions

This review highlights the different enantioselective catalyst-controlled cascades creating multiple alcohol functions through the formation of several carbon-carbon bonds. Through subsequent simple derivatization, these strategies ensure the rapid preparation of 1,3-polyols. Thanks to the use of efficient metal- or organo-catalysts, these cascades enable the selective assembly of multiple substrates considerably limiting operations and waste generation. For this purpose, several mono- or bi-directional approaches have been devised allowing successive C-C bond-forming events. The considerable synthetic economies these cascades enable have been demonstrated in the preparation of a wide variety of complex bioactive natural products, notably polyketides.

Diastereoselectivity in the boron aldol reaction of α-alkoxy and α,β-bis-alkoxy methyl ketones

In this work, using DFT calculations, we investigated the 1,4 and 1,5 asymmetric induction in boron enolate aldol reactions of α-alkoxy and α,β-bisalkoxy methyl ketones. We evaluated the steric influence of alkyl substituents at the α position and the stereoelectronic influence of the oxygen protecting groups at the α and β positions. Theoretical calculations revealed the origins of the 1,4 asymmetric induction in terms of the nature of the β-substituent. The synergistic effect between the α,β-syn and α,β-anti-bisalkoxy stereocenters was elucidated. In the presence of the β-alkoxy center, the reaction proceeds through the Goodman-Paton 1,5-stereoinduction model, experiencing a minor influence of the α-alkoxy center.

The total synthesis of calcium atorvastatin

A practical and convergent asymmetric route to calcium atorvastatin (1) is reported.

Didecarboxylative Iron-Catalyzed Bidirectional Aldolization towards Diversity-Oriented Ketodiol Synthesis

1,3-Acetonedicarboxylic acid was selectively activated by Fe(acac)3 , providing a synthetic platform for rapid synthesis of keto-3,3'-diols. The bidirectional aldol reaction was efficient for challenging aliphatic aldehydes, providing a rapid route to potentially bioactive complex structures.

The total synthesis of (−)-cryptocaryol A

A stereoselective total synthesis of (−)-cryptocaryol A (1) is described. Key features of the 17-step route include the use of three boron-mediated aldol reaction–reduction sequences to control all stereocenters and an Ando modification of the Horner–Wadsworth–Emmons olefination that permitted the installation of the Z double bond of the α-pyrone ring.