Merck + Co., Inc.

Daisy Joe

Ralph P Volante

Ichiro Shinkai

David Askin

An intermediate, useful in the conversion of FK-506 to FK-525 and analogous 23-membered ring macrolides, of the structure: ##STR1##

FK-506 type macrolide intermediate

A process for the conversion of FK-506 (I,R=allyl;1) to FK-525 (XV) and analogous 23-membered ring macrolides differing in the C.1-N.7 segment of the molecule (e.g. XVI) and is also applicable to the analogs FK-523 (XVII) and FK-520 (XVIII). The overall process consists of three stages: (a) initial degradation of the primary macrolide to an acyclic fragment containing a selectively protected C.10-C.34 framework with a protected aldehyde function at C.10 and a free hydroxyl function at C.26, (b) reacylation of the C.26 hydroxyl function with an appropriately N-protected alpha-amino acid moiety, and (c) reintroduction of the C.8 and C.9 carbons followed by regeneration of the FK-macrolide system.

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Daisy Joe