Total synthesis of (+)-laurencin. Use of acetal-vinyl sulfide cyclizations for forming highly functionalized eight-membered cyclic ethers

…, WH Bullock, LE Overman, T Takemoto

Index: Bratz, Matthias; Bullock, William H.; Overman, Larry E.; Takemoto, Tadahiro Journal of the American Chemical Society, 1995 , vol. 117, # 22 p. 5958 - 5965

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Citation Number: 104

Abstract

Abstract: The enantioselective total synthesis of (+)-laurencin (1) is accomplished in 24 steps from allyl alcohol. The synthesis features an acetal-vinyl sulfide cyclization that forms the oxocene ring and introduces, with complete control, the A4 unsaturation and requisite functionality at carbons 3, 4, and 9. Starting with allyl alcohol, mixed acetal 17 is constructed in seven steps and 38% overall yield (Scheme 2). Exposure of 17 to excess BFyOEt2 in t- ...