Synthesis of 3a-methylene-3β, 5β-ethano-B-nor-5β-androstane 6β-carboxylic acid (1) having a gibbane B-C-D ring system is described. 5β-Cyano-6β-vinyl-B-nor-5β-androstan-3-one (5), the starting material, was transfomed stereoselectively to 3α-tosyloxy-5β-(trans-β-formyl) vinyl-6β-vinyl-5β-androstane (22d), the key intermediate, by theeight-step synthesis. The latter, after selective ozonization was subjected to a newcyclization method involving Participation of 6β-hemiacetal function to afford 3β, 5β-etheno derivative (38), which on subsequent oxidation and the Wolff-Kishner reduction, led to the desired compound (1). Some attempted experiments for homologation atthe 5β-nitrile function are also described.