Ring Closing Metathesis Mediated Synthesis of 4a-Aryloxodecahydroisoquinolines, Intermediates in the Preparation of Novel Opiates

The concise syntheses of the 4a-aryldecahydroisoquinolines 1 and 2 through a uniform strategy starting from N-methyl-3-allyl-4-piperidinone are reported in this Letter. Key transformations include a ring closing metathesis reaction to prepare a trans-octahydroisoquinoline common intermediate and a regiocontrolled hydroboration−oxidation sequence.