Indole 3-carbanions*, generation

In a new development in alkaloid synthesis, Myers and Hellring have shown that the p-amino-carbanion from tetrahydro-p-carboline can be employed as a precursor for the ring systems (103), (104), and (105), which are found amongst natural indole alkaloids. Thus, the conversion of tetrahydro-P-carboline into the amidine derivative (101), followed by protection of the indole nitrogen and treatment with t-butyl-lithium, generated the (3-amino-carbanion (102). Addition of various electrophiles, followed by further manipulations of the functional groups, then led to the alkaloid ring-systems (103), (104), and (105). 

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