Synthetic studies on spiroketal natural products. IV. A stereoselective synthesis of (3S,5S,6R,9R,R(S))-3-benzyloxymethyl-9-hydroxymethyl-5-(p-tolyl)sulfin yl-1,7-dioxaspiro[5.5]undecane, a key intermediate for talaromycins

Article abstract of DOI:10.1248/cpb.41.339

A dioxaspiro compound (4), a common intermediate for the synthesis of talaromycin A (1) and (-)-talaromycin B (2), was synthesized by two routes utilizing two kinds of asymmetric recognition of prochiral 1,3-diols controlled by sulfinyl chirality, that is, firstly by acid promoted diastereoselective C-O bond fission of the bicyclic acetal (7) to give the dihydropyran derivative (6), which has an S-hydroxymethyl group at the C3-position (7 → 6), and secondly by diastereoselective intramolecular Michael addition of the diol (5), in which the three chiral centers at C5, C6, C9 were constructed in one step (5 → 4).

Full text of DOI:10.1248/cpb.41.339

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