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20.5.1.3.1.2.1.2 Variation 2: Using the Hetero Aldol–Tishchenko Reaction

DOI: 10.1055/sos-SD-020-00673

Yan, L.; Lin, S.; Liu, P.Science of Synthesis, (200720745.

The hetero aldolTishchenko reaction involves the condensation of a molar equivalent of an enolizable aldehyde (or ketone) with 2 equivalents of a different aldehyde (R3CHO) to generate the monoester 63 of an anti-configured 1,3-diol. Excellent diastereoselectivity is achieved under mild conditions but, in order to avoid side reactions and to allow the desired reaction to proceed selectively, the first carbonyl compound (particularly, when it is a ketone) is usually converted into a metal enolate 61. This condenses with the aldehyde to form a metalated aldol 62, which combines with another equivalent of the aldehyde to give a metal-coordinated cyclic adduct within which hydride transfer occurs to complete the process (Scheme 21).

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