Tetracyclic diketone, preparation

Tetracyclic ring system 741 was prepared by condensation of 739 with a-diketones to give 740, whose treatment with /3-diketones gave 741 (73MI1 80UKZ1092) (Scheme 153). 

Synthesis ofLysergic Acid, By reacting N-benzoyl-3-(B-carboxyethyl)-dihydroindole (see JCS, 3158 (1931) for the preparation of this compound) with thionyl chloride, followed by aluminum chloride gives l-benzoyl-5-keto-l,2,2a,3,4,5-hexahydrobenzindole. This is then brominated to give the 4-bromo-derivative, which is converted to the ketol-ketone by reacting with methylamine acetone ethylene ketol. This is then hydrolized by acid to yield the diketone and treated with sodium methoxide to convert it to the tetracyclic ketone. Acetylate and reduce this ketone with sodium borohydride to get the alcohol, which is converted to the hydrochloride form, as usual. 

The Hinsberg reaction has been used in two cases to prepare tetracyclic condensed thiophenes from 1,2-diketones and thiodiglycolic esters.68 One example is shown in Scheme 7 for the synthesis of 29 (13% overall).43,69 If water is not added during the process, one isolates the half-ester (27% for methyl half-ester of 207), which undergoes decarboxylation with copper... 

In this section we must also mention the syntheses of cyclopentano-phenanthrene derivatives described in Scheme 88. These include, in the first place, attempts to apply the Robinson synthesis (Chapter II, Schemes 24 and 25) to the preparation of tetracyclic products with an angular methyl group at CiQ. By this method, for example, from the acetylmethylcyclo-hexene (63) and 1,5-decalindione (4) it was expected to obtain the diketone (65) through a sequence of Michael addition reactions and intramolecular crotonic condensation. However, it was found that the presence of the ce-methyl group in the acetylcyclene (63) suppressed the Michael reaction and... 

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