ISSN:
0018-019X
Keywords:
Chemistry
;
Organic Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
Treatment of 2β-tosyloxy-A-nor-5α-cholestane-5-ol (2) with t-butoxide in t-butanol gave 2α, 5-epoxy-A-nor-5α-cholestane (3) in quantitative yield.When A-nor-5β-cholestane-2α, 5-diol (4) was treated with tosyl chloride in pyridine 2β-chloro-A-nor-5β-cholestane-5-ol (7) and 2α-tosyloxy-A-nor-5β-cholestane-5-ol (8) were obtained. Whereas the chloride 7 was resistant to t-butoxide the tosylate 8 was transformed into an 1 : 1 mixture of 2α, 5-epoxy-5β-cholestane (10) and 2ξ-t-butoxy-A-nor-5β-cholestane-5-ol (11). In 2α-tosyloxy-A-nor-5α-cholestane-5-ol (12) substitution occurred as the only reaction.Both oxetanes 3 and 10 isomerize after heating above 50° and in polar or protic solvents to form A-nor-Δ3(5)-cholestene-2α-ol (6) and -2β-ol (14) respectively. Also, 2, 5-diols are encountered.2α-Ethyl-2β, 2′-epoxy-A-nor-5α-cholestane (23) was synthesized starting from A-nor-5α-cholestane-2-one (17). The intermediates were the ester 16, the diol 18, the hydroxy-tosylate 19 and the chlorhydrin 20. The spirocyclic oxetane 23 was reduced by LiAlH4 in dioxane (not in ether). By chromatography on silica gel 23 was isomerized to the homoallylic alcohol 21 and transformed into 2-methylene-A-nor-5α-cholestane (24) by fragmentation.The IR. and NMR. spectra of the new oxetanes were compared with those of a series of known oxetanes.
Additional Material:
3 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/hlca.19680510508
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