Ring closing metathesis mediated synthesis of 4a-aryloxodecahydroisoquinolines, intermediates in the preparation of novel opiates

[GRAPHICS] The concise syntheses of the 4a-aryldecahydroisoquinolines 1 and 2 through a uniform strategy starting from N-methyl-3-allyl-4-piperidinone are report ed in this Letter. Key transformations include a ring closing metathesis re action to prepare a trans-octahydroisoquinoline common intermediate and a r egiocontrolled hydroboration-oxidation sequence.