Tryptophan requirements for

Enantiomerically pure 4-alkyl substituted derivatives of tryptophan required for the asymmetric syntheses of ergot alkaloids has been obtained [35]. The author used the method [36] to produce 4-alkyl substituted indoles and combined this organometallic reaction with an enantioselective enzymatic transformation. An efficient eight stage synthesis ofN-benzenesulphonyl-3-(3 -methoxyprop-2 -en-r-yl)-4-(r-hydroxy-2 -trimethylsilymethyl-prop-2 -en-r-yl)-indoles from 4-carbomethoxyindole has been described [37]. The use of these benzylic alcohols for intramolecular cation-olefine cycloadditions yielding either a tetracyclic or a tricyclic product was also demonstrated. 

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