Aldol reactions retrosynthetic analysis using

In comparison to other aldolases, DERA has a rather broad substrate range. DERA-catalyzed aldol reactions were used to get an access to key intermediates for epothilones (Fig. 36) [194]. According to retrosynthetic analysis, both fragments of the molecule could be obtained from aldol building blocks, and two out of seven stereocenters were established enzymatically. For the southern part of epothilone A,... 

Thus the two mandelic acid-based boron enolates described in this section may be regarded as sources of propionic acid which add to aldehydes to give erythro aldol products of high stereochemical purity. An elegant synthesis of the macrolide, 6-deoxyerythronolide B, uses three mandelic acid-based boron enolate/aldehyde reactions. The retrosynthetic analysis of the synthesis is shown in Figure B5.ll. 

Inspired by the biosynthesis of carbohydrates we envisaged a direct de novo synthesis of carbohydrate derivatives by using the DHA-equivalent 4 in a C3+Cn-sirategy. As can be seen from the retrosynthetic analysis, the desired building blocks 5 should be prepared from the dioxanone (4) and an aldehyde component 6 in an organocatalytic aldol reaction... 

The functional groups created by the aldol reaction are a j8-hydroxy carbonyl or an a,)8-unsaturated carbonyl. Whenever you encounter these patterns in a target molecule, you should consider using an aldol reaction for its construction. Using retrosynthetic analysis (Section 7.9), the aldol product can be dissected into the... 

Some students confuse retrosynthesis with a reverse reaction, especially in the case of aldol reactions, because aldol reaction are reversible. Retrosynthetic analysis of an aldol product is a thought exercise used to figure out which aldehydes or ketones must be combined to make the target. A reverse aldol reaction is an actual reaction in which the product is hydrolyzed, using water and a catalyst, back into the aldehydes or ketones that were used to make it. 

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