Aminoindanol and Related Chiral Auxiliaries

Ghosh and coworkers developed novel highly diastereoselective anti aldol methods based on ester-derived titanium enolate aldol reactions [64-66]. The utility of the as-l-toluenesulfonamido-2-indanol-derived chiral auxiliary was demonstrated. This chiral auxiliary is readily prepared from commercially available enantiomerically pure ds-l-amino-2-indanol. Both enantio- 

Reaction with several other aldehydes also produced the anti isomer as the major product. It should be noted that of four possible diastereomers, only one syn and one anti product were observed in this reaction. The antv.syn selectivity ranged from 85 15 to 99 1 and yields ranged from 41-97%, as shown in Table 2.33. Whereas benzaldehyde resulted in very little to no selectivity under these conditions, in the presence of an additive there was a dramatic improvement in anti diastereoselectivity. Thus, aldol reaction of the enolate of 189 with benzaldehyde (2 equiv.) precomplexed with TiCl4 (2.2 equiv.) in the presence of CH3CN additive (2.2 equiv.) afforded anti al- 

Structure-reactivity relationship studies in anti aldol reactions. 

4 Addition of Enolates with a-Substituents to Aldehydes 103 TsNH 

Double stereodifFerentiation in aminoindanol-derived anti aldol reaction. 

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