Experimental studies in the steroids; a novel method for the preparation of sterol dichlorides

C J BERG, E S WALLIS
1946 Journal of Biological Chemistry  
As is well known, the sterols are monohydric polycyclic secondary alcohols, many of which are unsaturated at the 5,6 position. The various sterols differ in the number of double bonds and in the structure of the side chain. (0 One of the more important reactions in sterol chemistry is the temporary inactivation of the double bond in the 5,6 position. Permanent inactivation is generally brought about by hydrogenation (1). Temporary inactivation has been effected by the addition of bromine (2) or
more » ... by conversion to the i-ethers ((3), cf. (4) ). In the case of free bromine, the reaction is very rapid and the yield of dibromide is generally good. That this is a temporary protection of the double bond is shown by the fact that zinc and acetic acid will remove the bromine atoms. With free chlorine the results of the reaction are very different. Most of the product is oily and chlorine is apt to enter into many places in the sterol molecule. The desired crystalline dichloride is hard to obtain and the yield is very poor. It should be noted, however, that in many cases the dichloride would be preferable for synthetic work, since it is relatively more stable. It is our purpose in this paper to discuss the result,s of experi-
pmid:21018775 fatcat:pdc3p5fwkrefdbty7zctwsl6tq