In two recent publications Schmid and Kagi (1) and Shoppee and Evans (2) reported the results of their studies on the rearrangement of epicholesteryl p-toluenesulfonate. These authors hoped that a new isomeric 3-5-cyclosterol, a 3-5-cyclocoprostanyl derivative, could be prepared via this rearrangement. Such a compound, as a derivative of coprostane, would have the C3-C5 bond in front of the plane of the A ring and a cis A/B ring fusion, while the normal 3-5-cyclosterol is related to cholestane. However, no 3-5-cyclosterol was found among the reaction products: the products of the reaction in methanol with potassium acetate were 3• 6-cholestadiene, in a predominant yield, 4/3-methoxy-A6-cholestene, designated as "ether B", and 6/S-methoxy-A4-cholestene, designated as "ether A."In the light of these results, it was decided in this laboratory to investigate this rearrangement in aqueous acetone with potassium acetate at room temperature, in the hope that the milder conditions would inhibit the elimination reaction leading to 3 > 5-cholestadiene and be more favorable to the formation of a 3-5-cyclocoprostanyl isomer.Epicholesterol was prepared via the method described by Plattner, et al.(3). It was found that the cholesteryl -oxide used in this synthesis may be very readily prepared with peracetic acid. The yields are comparable to those obtained by the use of perbenzoic acid and the rather tedious preparation of this peracid is avoided. The -oxide so prepared melted at 142-144°.Epicholesteryl p-toluenesulfonate (I) was prepared by the standard method of treating the sterol with p-toluenesulfonyl chloride in pyridine. The crude product of the reaction of I with potassium acetate in aqueous acetone was chromatographed on alumina to give a 60% yield of 3• 6-cholestadiene (II), and a 16 % yield of a compound identified on the basis of its analysis, infrared spectrum, and rotation as A6-cholesten-4jS-ol (III), m.p. 131-132°, [aj^3 -60°. This alcohol (III) upon methylation gave 4/3-methoxy-A'-cholestene (IV), m.p. 65.5-66.5°, [«]" -73°, whose infrared spectrum was identical with that obtained by Schmid and Kagi for "ether B" (1).The recent work of Reich, et al. ( 5) provided the synthetic approach to the A4-cholesten-6a-and 6/3-ols. These authors prepared A4-cholesten-6-one (VIII)