Formal total synthesis of clausenamide

Ruthenium tetroxide oxidation of trans-5-substituted 4-acylaminocyclohexenes 2 followed by esterification gave N-protected cis-4-substituted 5-(methoxycarbonylmethyl)-2-pyrrolidones 4. The resulting pyrrolidone 4a (N-Boc-4-phenyl) was converted into the key intermediate 8 (cis-5-formal-1-methyl-4-phenyl-2-pyrrolidinone), thus achieving the formal total synthesis of clausenamide [3-hydroxy-5-(α-hydroxybenzyl)-1-methyl-4-phenyl-2-pyrrolidinone].