Alkaloids Lacking the Tryptamine Bridge

A number of new uleine-like alkaloids were briefly described in Volume VIII (p. 473). These are listed in Table I and details of their chemistry have now been published (2, 39). NMR (39a) and methiodide formation rates (86a) show that the 3-ethyl group of these bases is oriented away from Ab- The 3-epimers of uleine and dasycarpidone have been isolated (39a). De-ethyldasycarpidone has been synthesized (86b). 

H2C=C—CH(Y)—CH2— CH2—X (X and Y are N or double bonds). These sequences may only be found in CCLXXII and this leads to structure CCLXX for apparicine itself (S i ). An alternative invert structure CCLXXVI for apparicine was excluded on biogenetic grounds (43). The names pericalline, tabernoschizine, and gomezine are synonjnns of apparicine (S6). 

The mass spectrum of vallesamine (CCLXXVII) is characterized by a primary loss of the oxygen functions after which the pattern resembles that of apparicine. The ring C open derivatives cleave first at C-1, C-2 and the fragmentation of these was followed by comparison of the spectra of CCLXXIX, CCLXXXII, CCLXXXV, CCLXXXIV, its deuterated derivative CCXCIV, and the diol CCXCV 43). 

The antitumor activity of these alkaloids has led to renewed interest in their synthesis. Saxton s synthesis of ellipticine (CCXCVI Volume VIII, pp. 477-480), the most adaptable to large-scale production, has been shortened by two steps by the direct cyclization of the intermediate (CCXCVII) in 90-100% phosphoric acid. The same route has been used to synthesize 9-methoxyellipticine (CCXCIX) from 5-methoxyindole (CCXCVIII) 88). This alkaloid, earlier thought to be 8-methoxy-ellipticine (CCC) on the basis of UV- and fluorescence-spectra 47), is identical with the methoxyellipticine referred to in Volume VIII. 

Schmutz and Wittwer s synthesis of olivacine (CCCVII) has been improved and adapted to the preparation of modified pyridocarbozoles 90). Among simpler derivatives that have been prepared are CCCVIII 90) and CCCIX 89). 9-Methoxyolivacine has been found naturally (Table I, 55e). 

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