A-Hydroxylactams

In the same manner, compound 154, treated by hydrogen in the presence of Pd(OH)2/C in methanol, was transformed to the a-hydroxylactam 155 (Equation 23) <20010L1367>. 

Other fused azepines, with aromatic (e.g. 94a,b) or heteroaromatic fused rings (e.g. 94c,d) have been prepared via the Af-acyliminium ion intermediate 93 in high yields lactam reduction then yielded the respective amines 95a,b and 95c,d [01H1519]. An intramolecular Friedel-Crafts reaction has been used to synthesise the fused azepinone 99 (S,S configuration) from 98, the latter being prepared from the diastereopure a-hydroxylactam 96, via the acid 97 [02H449],... 

Attempts to extend this work to the keto-oxime substrate 54 derived from D-glucosamine with an JV-phthalimido group resulted in the formation of a completely different product (Scheme 40). In this case, cyclization was initiated by reduction of the phthalimido carbonyl group to its corresponding ketyl radical anion followed by cyclization onto the ketone, providing an a-hydroxylactam 55 which was proposed to be a potentially useful scaffold for diversity-oriented synthesis. 

The microbiological oxidation of coronaridine (229) by means of Sporotrichum sulfurescens affords a phenolic derivative (230) of uncertain orientation, together with a lactam (231) identical with an alkaloid previously isolated from Conopharyn-gia jollyana Stapf., and a hydroxylactam, provisionally formulated as (232). The action of Cunninghamella blakesleana Lendner leads to a hydroxycoronaridine, which is suspected to be (233). 

EtOH). Nuttalline is a hydroxylactam of the sparteine series, and exhibits i.r. absorption bands characteristic of a trans-quinolizidine derivative its properties indicate that it is (-b )-4a-hydroxy-2-oxosparteine (4), and it is the first example of a naturally-occurring 2,4-dioxygenated sparteine. Nuttalline gives a complicated mixture of products when reduced by lithium aluminium hydride, but with sodium borohydride affords deoxonuttalline [(— )-4a-hydroxy-sparteine], which can be converted by dehydration and hydrogenation into (—)-sparteine. 

A total synthesis of (-)-anisomycin (1) from malimide has been achieved by a highly regio and trans stereoselective reductive alkylation of (S)-M,0-dibenzyl malimide 117 (Scheme 14) [85]. Reductive alkylation of (S)-lM,0-dibenzyl malimide 117, prepared from (S)-malic acid [86], with p-methoxybenzylmagnesium chloride gave the a-hydroxylactam 118 as a di-astereomeric mixture. Hydroxylactam 118 in the presence of 3 equivalents of boron trifluoride etherate was reduced with excess of triethylsilane to yield predominantly trans-119 in 94.8% yield. Catalytic hydrogenation of 119 afforded 120 in quantitative yield which was reduced to pyrrolidine 121 in 90%... 

Scheme 1.28 Pictet-Spengler-type cyclization of a hydroxylactam in the synthesis of (+)-harmicine...

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