The action of toluene-p-sulphonyl chloride in pyridine on
cholest-4-en-3ß-ol and on 5a-cholest-l-en-3ß-ol has been investigated; in neither case was a tosyl ester isolated. The former
reaction produced 3a,5-cyclo-5a-cholest-6-ene, cholesta-3,5-diene
and N-(cholest-4-en-3a-yl)-pyridinium tosylate. In the latter
case, the products isolated were la,5-cyclo-5a-cholest-2-ene and
N-(cholest-l-en-3a-yl)-pyridinum tosylate.la,5-Cyclo-5a-cholest-2-ene has been characterised by both
its spectral properties and chemical reactions. The ultra violet
and infra red spectra are consistent with the assigned alkyl-cyclopropane structure; indeed the proton magnetic resonance
spectrum also supports the structure, but assignment of peaks
was uncertain. The ambiguity was resolved by consideration of
the p.m.r. spectrum of 17ß- methoxy-la,5-cyclo-5a-androst-2-ene,
synthesised from 17ß-methoxy-5a-androst-l-en-3ß-ol by the same
method. This reaction also produced l7ß- methoxy- 5a- androsta-1,3-diene in addition to the cyclosteroid.The major reactions of la,5-cyclo-5a-cholest-2-ene are
summarised below. Catalytic reduction using palladium on
charcoal catalyst afforded 5a-cholestane, but use of the soluble
catalyst, tris(triphenylphosphine)rhodium chloride, gave la,5-cyclo-5a-cholestane. Oxidative fission of the olefinic bond
followed by reductive cleavage of the cyclopropane ring afforded
the known diacid, 2,3-seco-cholestan-2,3-dioic. Reaction of
peracid with the hydrocarbon gave a mono-oxide, cleaved with
lithium aluminium hydride to give 1a,5-cyclo-5a-cholestan-2a-ol.
The cyclopropyl-ketone obtained from the oxidation of this alcohol
was reduced catalytically to dive 5a-cholestan-2-one. la,5-Cyclo-5a-cholestane was obtained from this ketone by Wolff- Kishner reduction.la,5-Cyclo-5a-cholestane has also been synthesised by a
separate reaction sequence, the cyclopropane ring being introduced
by dehydration of a suitably substituted 5ß-hydroxy compound, and
proved to be identical with the material obtained in the above
reactions.A possible mechanism for the formation la,5-cyclo-5a-cholest-2-ene from 5a-cholest-l-en-3ß-ol has been proposed, involving
transannular migration of the 5a-hydrogen atom. Results from
tosylation experiments on 5a-deutero and 5a-fluoro-cholest-l-en3ß-ol have substantiated this mechanism.Attempted tosylation of 19-nor-androst-4-en-3ß-ol and 19-nor5a-androst-l-en-3ß-ol gave estra-3,5(10)-diene and estra-l,3-diene
respectively; no cyclosteroids were isolated.A synthesis of estradiol from 17ß-acetoxy-androst-1,4,6-trien3-one has been carried out. Aromatisation of this trienone with
sulphuric acid under anhydrous conditions gave 17ß-acetoxy-l-methyl-estra-1,3,5(10) -trien-3-one. Removal of the l-methyl
group was effected in two stages: Oxidation with cerium (IV)
gave the l-formyl derivative, which was decarbonylated with tris-(triphenylphosphine) rhodium chloride
