Steroidal Cyclobutanones, IV. Heterocyclic Spiroannulation of 5α‐Cholestan‐3‐one. Stereospecific Beckmann Rearrangement of Steroidal 3‐Spirocyclobutanone Oximes

Authors:

• Krzysztof Blaszczyk,
• Zdzisław Paryzek

Abstract

Diastereomeric 5α‐cholestane‐3,3′‐spiro‐2′,2′‐dichlorocyclobutanones 1 and 2 served as starting materials for the synthesis of related heterocyclic spirane derivatives. Thus, diastereomeric 5α‐cholestane‐3,3′‐spiropyrrolidin‐5′‐one (10, 11), ‐3′‐spiro‐γ‐lactone (12, 16), and ‐3′‐spirotetrahydrofuran (14, 18) are described. The spirocyclobutanone oximes (E)‐4 and (Z)‐5 and their O‐acetyl and O‐benzoyl derivatives 6, 7 and 8, 9 are also prepared. It has been shown that the Beckmann rearrangement of the spirocyclobutanone oximes 4 and 5 proceeds stereospecifically with exclusive anti migration. The stereochemistry of the spiro compounds is assigned on the basis of the ¹H‐ and ¹³C‐NMR spectral data. Copyright © 1993 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim