Poly ether antibiotics synthesis

Hydroboration of alkenes1 (15, 91). The Rh(I)-catalyzed hydroboration provides a highly diastereoselective reaction in a synthesis of a poly ether antibiotic. Thus the derivative (1) of an acyclic allylic alcohol is converted to the primary alcohol 2 by hydroboration with catecholborane (CB) catalyzed by ClRh[P(C6H5)3]3 with 94 6 selectivity. Note that hydroboration of 1 with disiamylborane (12, 484) proceeds with the opposite selectivity at Cio (8 92). 

Horita, K, Inoue, T, Tanaka, K, Yonemitsu, O, Stereoselective total synthesis of lysocellin, the representative poly ether antibiotic of the lysocellin family. Part 1. Synthesis of C1-C9 and C16-C23 subunits. Tetrahedron, 52, 531-550, 1996. 

In a total synthesis of the poly-ether antibiotic lasalocid A, the key intermediate (5) (Scheme 11) was prepared by sequential epoxidation of the keto-diene (4) subsequent transformations led to synthetic lasalocid A (6). 

Development of diastereoselective and enantioselective aldol reactions has had a profound impact on the synthesis of two important classes of natural products—the macrolide antibiotics and the poly ether ionophores. The aldehyde and the enolate involved in aldol reactions can be chiral, but we shall discuss only the case of chiral enolates. 

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