Synthesis and Formation Mechanism of a Compound with an Unprecedented Skeleton: Dodecahydro-4,10:5,9-diepoxydipyrrolo[3,4-b:3′,4′-f][1,5]diazocine

Abstract

The reaction of N-(2-{[(tert-butyldimethylsilyl)oxy]imino}ethyl)-4-methyl-N-(3-phenylprop-2-yn-1-yl)benzenesulfonamide (6b) with BF₃·OEt₂ afforded a compound with an unprecedented dodecahydro-4,10 : 5,9-diepoxydipyrrolo[3,4-b:3′,4′-f][1,5]diazocine skeleton (7) after aqueous work-up. The formation mechanism of meso-7 appears to involve dimerization of the hydrated forms (6aS)-C and (6aR)-C of the initial racemic product 9 via cation B generated by facile protonation at the C3a position of 9. Extensive computational studies revealed that the driving force of the facile hydration of 9 is probably release of the ring strain of 9, which arises in part from the bent sp²-hybridized C3a carbon.

Graphical Abstract