Enantioselective Synthesis of the C7-C24 Segment of Macrolactin A

Abstract

The C7-C24 tetraene triol segment of macrolactin A was prepared using organoiron chemistry. Two (carbonyl)iron moieties are responsible for stereoselective preparation of the C8-C11 E,Z-diene, as well as the C-15 and C-24 sp³ stereocenters. Furthermore, this iron complexation serves to protect the C8-C11 and C16-C19 diene groups during reductive hydrolysis of an isoxazoline group.

Key words

polyene macrolide - (diene)iron complexes - nitrile oxide-olefin cycloaddition - remote asymmetric induction

References

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10

2-Trimethylsilylethyl nitroacetate was prepared by Ti(OEt)₄-catalyzed transesterification of ethyl nitroacetate with 2-trimethylsilylethanol (56%).

20

Notably, others have reported that removal of hydroxyl protecting groups from intact macrolactin A has proven to be difficult (cf. Ref. [4b] ).