• Lalitha Krishnan

      Articles written in Journal of Chemical Sciences

    • A total synthesis of 4-cyano-1,3-dimethoxy-2-azaestra-1,3,5(10)-trien-17β-ol and its configuration assignment

      T R Kasturi Lalitha Krishnan

      More Details Abstract Fulltext PDF

      A total synthesis of 4-cyano-1,3-dimethoxy-2-azaestra-1,3,5(10)-trien-17β-ol(6a) has been achieved starting from 4-cyano-1,3-dimethoxy-5,6,7,8-tetrahydroisoquinoline(1a). Dichromate oxidation of1a gave the 8-oxo derivative(1c) whose structure was confirmed unambiguously by the lanthanide induced chemical shift method. Grignard reaction of1c with vinyl magnesium bromide followed by condensation of the vinyl-alcohol with 2-methyl-cyclopentane-1,3-dione resulted in the seco-dione(2) in 50% yield, which was cyclised withp-toluene sulfonic acid to the pentaenone(3a). Sodium borohydride reduction of3a, stereoselective partial hydrogenation of the 14,15-double bond in3b followed by isomerisation of the 8,9-double bond in4 to 9,11-position and catalytic reduction of the 9,11-double bond gave the title compound(6a). The 14α, 8β, 9α-configuration in6 was tentatively assigned on the basis of its NMR spectrum. The CMR spectra of the steroidal derivative and also the tetrahydroisoquinoline derivative(1b) have been studied and the configuration assigned to the steroid has also been supported by this study.

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