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Keys to the kingdom: A highly efficient and diastereoselective transannular oxy-Michael reaction for the construction of the syn- and anti-tetrahydropyran units from a common 14-membered macrolactone is the key step for the total synthesis of aspergillide A and B (see scheme; CM=cross-metathesis, HWE=Horner–Wadsworth–Emmons, TBS=tert-butyldimethylsilyl).
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Kanematsu et al. (2011) studied this question.
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