The stereochemistry of ethyleneimines fused to six-membered rings (original) (raw)

BY studying the reactions of a number of steroidal epoxides, Barton has formulated the "rule of diaxial opening" which has come to be one of the fundamental tenents of conformational analysis. Ia2 Comparatively little effort has been expended, however, toward the elucidation of the stereochemistry of ring opening of analogous ethyleneimines. It has been shown that ethyleneimines undergo ring opening in a trans manner,""l but it remains to be shown whether or not this ring system opens in a diaxial manner when fused to a six-membered ring. We would now like to report the first synthesis of a steroidal ethyleneimine and evidence that the ring does indeed open in a trans -diaxial manner. 2-Cholestene was converted into an iodo-isocyanate I, m.p. 110.5-l lZ", It max 2260 cm-', in 90% yield upon treatment with iodine isocyanate in ether solution.b'r