Concise Stereocontrolled Synthesis of an α-Carbagalactose Segment of RCAI-56, a Candidate Anticancer Agent

Abstract

RCAI-56 is a synthetic glycolipid exhibiting a potent antitumor activity by stimulation of natural killer T cells. Tetra-O-benzyl-α-carbagalactose, an important synthetic segment of RCAI-56, was stereoselectively synthesized from 1,4-dichloro-2-butene in nine steps, including the key step of organocatalytic asymmetric Diels–Alder reaction between acrolein and 1-benzyloxybutadiene.

Key words

α-carbagalactose - glycolipid - RCAI-56 - Diels–Alder reaction - organocatalyst

• References and Notes

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A similar selectivity has been reported, although its origin of the selectivity has not been clarified yet. For examples, see:
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A basic condition (PhCHCl₂, pyridine, reflux) was employed for synthesis of the benzylidene acetal from 19 to give a 1:1.1 mixture of 20a and 20b. For the basic conditions, see:
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