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
✍ Scribed by Paryzek, Zdzislaw ;Błaszczyk, Krzysztof
- Publisher
- John Wiley and Sons
- Year
- 1993
- Tongue
- English
- Weight
- 594 KB
- Volume
- 1993
- Category
- Article
- ISSN
- 0947-3440
No coin nor oath required. For personal study only.
✦ Synopsis
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, the synthesis of spiro‐cyclopentane (3–6), spirocyclobutane (9, 11, 13, 17–20) and spirocyclopropane steroids (12, 14, 15) is described. The sterically dependent reaction of spiro‐α,α‐dichlorocyclobutan‐3‐ones with an excess of sodium methanolate in methanol is reported. Thus, the reaction of 1 with sodium methanolate gives 9, the product of the double cine substitution, while the corresponding reaction of compound 2, which is sterically more hindered for similar nucleophilic attack, gives mainly the spirocyclopropane 12. The stereochemistry of the spiro compounds is assigned on the basis of ^1^H‐ and ^13^C‐NMR spectra.