A new synthetic route to (±)-forskolin

Abstract:

The trans -decalin lactone (35) has been elaborated in five steps from the bromo-acetal (10) using a novel stereoselective intramolecular radical mediated cyclisation reaction, viz (10)→(12) in tandem with an intramolecular Mukaiyama aldolisation, viz (34)→(35). Treatment of (35) with methanolic potassium hydroxide next led to the βγ-unsaturated lactone (37), which on oxidation with pyridinium dichromate t-butylhydroperoxide complex then gave the enone (40). Since the enone (40) has previusly been converted to (±) -forskolin (1), the sequence constitutes a new synthetic route to this natural product. Some chemistry relating to elaboration of the cis -decalin lactone (49) to analogues of forskolin, e.g. (55), (56) and (57), incorporating a cis -ring fused decalin core structure, is also described.

Año de publicación:

1989

Keywords:

Fuente:

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