A convergent strategy was developed for the synthesis of the C12-C40 segment of (-)-pulvomycin. Key step was a diastereoselective aldol reaction between a chiral ethyl ketone representing the C24-C40 fragment and a chiral aldehyde representing the C12-C23 fragment. Both compounds were prepared from enantiomerically pure building blocks in a convergent fashion. The longest linear sequence commenced with a known D-fucose-derived glycosyl donor and entailed a total number of 16 steps. The desired anti-aldol product was obtained in a total yield of 5% over these steps and contains 12 out of 13 stereogenic centers present in the natural product.
In Scheme3 of this Research Article,t he triethylsilyl groups in structures 14, 16, 18 and 19 were incorrectly labelleda s" SET" rather than "TES". The corrected Scheme 3 is given below.Scheme3.Synthesis of the C1-C7 fragment 20 of pulvomycin Df rom iodide 14 and Weinreba mide 15.Conditionsfor the Pinnick-Lindgren oxidation: [26] NaOCl,N aH 2 PO 4 ,2 -methyl-2-butene, r.t. (tert-butanol/H 2 O = 1/1)
A synthetic route to the pulvomycin class of natural products is presented, which culminated in the first synthesis of a pulvomycin, pulvomycin D. Key elements of the strategy include a pivotal aldol reaction which led to bond formation between the C24‐C40 and the C8‐C23 fragment. The remaining C1‐C7 fragment was attached by a Yamaguchi esterification completing the assembly of the 40 carbon atoms within the main skeleton. Ring closure to the 22‐membered lactone ring was achieved in the final stages of the synthesis by a Heck reaction. The completion of the synthesis required the removal of six silyl protecting groups in combination with olefin formation at C26‐C27 by a Peterson elimination.
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