Stereochemistry of Perhydrophenanthrene Derivatives

The stereochemistry of the adduct between 1-phenyl-1:3-butadiene and acrolein has been studied. The reaction has been proved to produce a cis-configuration, and conflicting claims by earlier workers have been shown to be due to Inversion on the carbon atom a to the aldehyde group. Hydrolysis of the aldehyde bisulphite compound with acid or alkali gives a similar cis-trans isomerisafcion, but the use of formalin leads to retention of configuration. The existence of both a cis and trans series of 2-phenyl-cyclo-hexyl compounds derived from this has been demonstrated, and their relationship to a hexahydrofluorene and hexahydro-fluorenone established. Interconversion between the cis-and trans forms has been achieved in some cases. A new synthesis of cis-9-keto-as-octohydrophenan-threne is described in which 3-bromo-2-phenyl-qyelo-hexene is condensed with diethyl malonate followed by hydrolysis, decarboxylation, hydrogenation, and cyclisation. The reduction of trans-9-keto-as-octohydrophenan-threne has been shown to give mainly elimination of oxygen and the formation of a perhydpophenanthrene. A little cis-anti-trans-perhydro-9-phenanthrol is formed at the same time A synthesis of trans-anti-trans-9-keto-perhydro-phenanthrene from the corresponding perhydrodiphenic acid has been accomplished, but attempts to extend the scope of the method to produce other isomers were unsuccessful. The perhydrophenanthrene derivative obtained by a Diels-Alder reaction between di-Delta-1:1'-cyclo-hexene and maleic anhydride, with subsequent hydrolysis, esterification and catalytic hydrogenation over Raney nickel, has been shown to possess the cis-anti-trans configuration. The conversion of this and the product obtained by hydrogenation of the corresponding acrolein adduct, into a cis-anti-trans-9-keto-perhydrophenanfchrene, could not, however, be effected