4-Toluene sulphonic esters, synthesis

Nucleophilic substitution of toluene- -sulphonates (tosy-lates) and other sulphonic esters of secondary steroidal alcohols has received much attention, both in studies of reaction mechanisms, and also as a route for the conversion of alcohols into their epimers. One of the most important practical objectives has been the synthesis of 3a-hydroxy-5a-steroids, which include androsterone and a wide variety of metabolites of the steroid hormones, Tosylates of equatorial 3jS-alcohols (15) give 3a-alcohols or their derivatives (16) in acceptable... 

For the synthesis of (2/ ,2 / )-oscillol (II), the aglycone of oscillaxanthin (208), the AD was selected [1IJ. The starting material 3-methylbut-2-enol (12) was converted, with p-nitrobenzoyl chloride, into the ester 13 (yield 88%). After AD the diol 14 was converted, with p-toluene-sulphonic acid, into the acetal 15 and seven further steps gave the Cio-phosphonium salt 16 which, in a Wittig reaction with crocetindialdehyde (77) gave (2/ ,2 / )-oscillol (//) (Scheme 6). 

The maleopimaric and acrylopimaric adducts, aftCT a three-step synthesis with ethylene glycol catalyzed by p-toluene sulphonic acid (pTS A), followed by epychlorydrine and by acrylic or methacrylic acid, led to the formation of vinyl-type ester monomers (Fig. 4.19), which wctc then submitted to radical copolymerization with styrene and tested as metal coatings [ 103]. A similar approach to coating materials was recently applied to prepare unsaturated polyester resins based on resin acid adducts, glycols and maleic anhydride [104, 105]. 

Guthrie and co-workers (1971, 1973) have described the use of a copolymer containing preformed monosaccharide units as esters of vinyl benzoate or vinylbenzene sulphonate and styrene. This is the only example of a polymer-supported synthesis wherein the substrate is first linked to the monomer and then polymerized to give the polymer-bound substrate. High and uniform loading of the polymer has been possible in this way, leaving no unreacted sites on the polymer. These noncross-linked polymers are soluble in solvents such as benzene, toluene, acetone. 

---