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

✍ Scribed by Blaszczyk, Krzysztof ;Paryzek, Zdzislaw

Publisher: John Wiley and Sons
Year: 1993
Tongue: English
Weight: 561 KB
Volume: 1993
Category: Article
ISSN: 0947-3440
DOI: 10.1002/jlac.1993199301177

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✦ Synopsis

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 ^1^H‐ and ^13^C‐NMR spectral data.

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Steroidal cyclobutanones, III. The Synth

Steroidal cyclobutanones, III. The Synthesis and Stereochemistry of 3-Spiro-5α-cholestane Derivatives with Three-, Four-, and Five-membered Carbon Rings—A DoubleCine Substitution in Spiro-α,α-dichlorocyclobutan-3-ones

✍ Paryzek, Zdzislaw ;Błaszczyk, Krzysztof 📂 Article 📅 1993 🏛 John Wiley and Sons 🌐 English ⚖ 594 KB

## Abstract Diastereomeric [(3__S__)‐5α]‐ and [(3__R__)‐5α]‐2′,2′‐dichlorospiro‐[cholestane‐3,1′‐cyclobutan]‐3′‐ones (1 and 2), prepared by cycloaddition reaction of dichloroketene with 3‐methylene‐5α‐cholestane, served as starting material for the synthesis of the related spirane derivatives. Thus