Road, Pontypool, Monmouthshire N P4 8YH Attempts to devise a synthesis of lysergic acid from 3,4-dihydrobenz[c,d]indol-5(1H)-one (I) via methy\ Nacetonyl-N-(I ,3,4,5-tetrahydro-5-oxo-l -(p-tolylsulphonyl)benz[c,d]indol-4-yl)carbamate (23) failed owing to difficulties in cyclising the latter to the tetracyclic ketone (4).Several alternative routes were examined and, inter alia, 4,8,9,1 Oa-tetrahydro-9-(hydroxymethyl) -9-methyl-6Hindolo [3,4-gh] [I ,4] benzoxazinium chloride (30) and 4-acetyl-6.6a.7.8-tetrahydro-8-imino-4H-indolo [6,5,4-cd] indolium acetate (40) have been prepared.

Syntheses of derivatives of the isomeric 4-amino-? ,3,4,5-tetrahydrobenz[cd]indol-5-ols (1) and (6) and the structurally similar 4-amino-2a,3,4,5-tetrahydroacenaphthen-5-ols ( 2 2 ) and (28), and of certain N-alkyl and NN-dimethyl derivatives are described. Preparation of the tetrahydrobenz[cd] indole series was made possible by the use of the tosyl group for protection of the indole imino-group.

The preparation of 3.4-dihydro-1 -(p-tolylsulphonyl) benz[cd]indol-5(1 H)-one (2) and its conversion to a wide variety of 5-substituted tetrahydrobenz[cd] indoles are described, thus demonstrating the value of the N-tosyl protecting group in indole chemistry. Several reactions were also possible with the corresponding 1 -acetyl derivative (3). THE chemistry of 3,4-dihydrobenz[cd]indol-5( 1H)-one (1)is dominated by the inherent tendency of the molecule to undergo isomerisation to the more stable naphthalenoid system.2 Protection of the indole imino-group as its N-acetyl derivative overcomes this problem only to a limited extent since the protecting group is labile in alkaline media. A more promising protecting group should be the tosyl since the stability of N-tosylindole to mild alkali has already been reported by us ; removal of the protecting group may be easily achieved in reflux-

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Das aus dem Azidoketon (I) durch Ketalisierung (mit Äthylenglykol‐BF3‐di‐ äthylätherat) und Reduktion (mit LiAlH4 oder Hz/Raney‐Ni) dargestellte Aminoketal (IIa) wird mit Chlorameisensäuremethylester zum Urethan (IIb) umgesetzt.