Iodo-etherification

A simpler approach gave even better results. The prochiral diol 213 was cleanly monoacetylated by the same enzyme (98% yield, 98% ee) and iodo-etherification gave the required diastereoselectivity 215 with suitable functionality for the introduction both of the triazole and of the other side chain.57... 

This methodology was applied to a two-step sequence for the preparation of enantio-merically enriched dihydrobenzo[h]furans (Scheme 10.11) [46]. Rhodium-catalyzed allylic etherification of (S)-47 (>99% ee), with the sodium anion of 2-iodo-6-methyl-phenol, furnished the corresponding aryl allyl ethers (S)-48/49 as a 28 1 mixture of regioisomers favoring (S)-48 (92% cee). Treatment of the aryl iodide (S)-48 with tris(trimethylsilyl)silane and triethylborane furnished the dihydrobenzo[h]furan derivatives 50a/50b as a 29 1 mixture of diastereomers [43]. 

An asymmetric synthesis of the dihydrobenzo[, ]furan segment of epheradine C has been achieved by an iodo-trimethylsilane-mediated debenzylation-benzylic etherification (Equation 133) <2000J(P1)893>. 

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