Claisen rearrangement remote stereocontrol

Dianionic Claisen rearrangements of (E)- and (Z)-butenyl jS-hydroxy esters afford acyclic systems I and 2 containing three stereogenic centers. The reactions proceed with remote stereocontrol (see Section 1.6.3.1.1,5.1.1. p 3481)50S-509. 

The C4 stereocenter dominates the stereochemical outcome of the Ireland-Claisen rearrangements in appropriately substituted allyl silyl ketene acetals. For substrates lacking a C4 stereocenter, other more remote stereocenters may play a significant role in the stereochemical outcome. There are comparatively few cases of remote stereocontrol, so most examples will be described in this section. The stereocenters will be discussed based on their location relative to the allyl silyl ketene acetal. Carbons a to the Cl carbon will be designated Cl, alpha to C4, C4 and so on (Fig. 4.1). 

Scheme 7.20 Remote stereocontrol in the Eschenmoser-Claisen rearrangement.

The Simmons-Smith cyclopropanation reaction Stereochemically controlled epoxidations Regio- and Stereocontrolled Reactions with Nucleophiles Claisen-Cope rearrangements Stereochemistry in the Claisen-Cope rearrangement The Claisen-Ireland rearrangement Pd-catalysed reactions of allylic alcohols Pd-allyl acetate complexes Stereochemistry of Pd-allyl cation complexes Pd and monoepoxides of dienes The control of remote chirality Recent developments Summary... 

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