Synthesis of novel 16-spiro steroids: Spiro-7′-(aryl)tetrahydro-1H-pyrrolo[1,2-c][1,3]thiazolo-trans-androsterone hybrid heterocycles

The 1,3-dipolar cycloaddition of azomethine ylide derived in situ from the reaction of acenaphthylene-1,2-dione and 1,3-thiazolane-4-carboxylic acid to various exocyclic dipolarophiles synthesized from trans-androsterone and trans-dehydroandrosterone afforded a library of novel spiro[5′.2″]acenaphthylene-1″-one-spiro[16.6′]-(7′-aryl)-tetrahydro-1H-pyrrolo [1,2-c][1,3]thiazolo-trans-androsterone/dehydroandrosterone hybrid heterocycles respectively. These reactions proceeded stereo-specifically affording a single isomer of the 16-spiro steroids in excellent yields.

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► 1,3-Dipolar cycloaddition of azomethine ylide to steroidal dipolarophiles.
► Stereospecific synthesis of 22 novel 16-spiro androsterones/dehydroandrosterones.
► The azomethine ylide cycloaddition proceeds regioselectively.
► Structure of these 16-spirosteroids elucidated with 1 and 2D NMR spectroscopy.
► The absolute configuration determined by single crystal X-ray studies.