Crystal structure and stereochemistry of (PS*, 2S*, 3aS*)-hexahydro-2-(tert-butylvinylthiophosphinyl)-6,6- dimethylpyrrolo[1,2-b]isoxazole

The structure of the major product of the cycloaddition of 2,2-dimethyl-3,4-dihydro-2H-pyrrole N-oxide to tert-butyldivinylphosphine sulfide was analyzed by means of single-crystal X-ray diffraction technique. The analysis revealed two crystallographically independent molecules that differed in conformation of the fused five-membered heterocyclic rings. These rings were found to be two envelopes in one molecule and two half-chairs in the other. The studied compound was identified as an exo adduct of the expected erythro configuration and was found to favor a conformation in which the PS and ring C–O bonds were anti and the CC–PS moiety was in the s-cis array. C₁₄H₂₆NOPS, space group P¯1, a = 10.6004(7) Å, b = 12.3225(6) Å, c = 13.4404(7) Å, α = 104.073(4)°, β = 92.758(4)°, γ = 95.968(5)°, V = 1688.802(4) ų, Z = 4.