Other Fused Bicyclic 6-6 and 6-7 Rings

Compound 105 was prepared in several steps from Trp. It was further converted into tryptoquivaline, a toxic metabolite from Aspergillus fumiga-tus (79JA5084 83JA3709 84TL3865 84H224). 

It is well known that isothiocyanates react with a-AAs to give hydantoins, but methyl o-isothiocyanatobenzoate gives a tetrahydroquinazoline derivative (67HCA1440). 

After being converted into the hydroxamic acid, A-protected L-Pro was transformed in situ into the acylnitroso dienophile, which underwent cycloaddition with cyclohexadiene to give the bicyclic cycloadduct 108 (or its mirror image) (89TL7061). 

Several condensed 6-7 bicyclic systems have been prepared from AAs. Some Af -chloroacetylated AAs are photochemically transformed into heterocycles with a condensed seven-membered ring. For example, A-chloro-acetyl-D,L-w-tyrosine is easily cyclized into benzazepinone 109a on irradiation with a high-pressure mercury lamp (67JA1039 68JA776). 

Some condensed 6-6 heterocyclic systems with three or more heteroatoms have been generated from AAs. Derivatives of the pyrido[2,3-d]- or pyr-ido[3,2-d]pyrimidine systems 113 and 114 were prepared from 3-(or 2-)ethoxycarbonyl-2-(or 3-)isothiocyanatopyridine and AAs (90JHC413, 90JHC643). 

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