TANDEM MICHAEL ADDITION [3,3]SIGMATROPIC REARRANGEMENT PROCESSES .2. CONSTRUCTION OF CYCLOPROPA[3,4]PYRROLO[3,2-E]INDOL-4-ONE (CPI) UNIT OF ANTITUMOR ANTIBIOTIC CC-1065

Development of an alternative strategy for preparing 3-acetoxymethyl-2,3-dihydro-1-methylsulfonyl-6-methoxyindole 25 has been completed. Since 25 was an intermediate in a previous synthesis of the CPI unit 5 of the antitumour antibiotic CC-1065 1, this achievement constitutes a formal synthesis of the racemic compound 5. The key strategic element of the approach involves the tandem Michael addition-[3,3]sigmatropic rearrangement process of methyl propiolate 10 and benzyl N-hydroxy-N-(3-methoxyphenyl)carbamate 9, prepared from m-nitroanisole 19, to furnish indole 8 as the sole product. Subsequent elaboration of compound 8 into indoline 25 was then achieved by applying Cava's technique. The conversion of 25 into 5 was also demonstrated on the basis of the well-established Wierenga's procedure.