TY - JOUR T1 - Construction of the 5,10b-phenanthridine skeleton using [3+2]-cycloaddition of a non-stabilized azomethine ylide: total synthesis of (+/-)-maritidine and (+/-)-crinine alkaloids JF - European Journal of Organic Chemistry Y1 - 2011 A1 - Pandey, Ganesh A1 - Gupta, Nishant R. A1 - Gadre, Smita R. KW - alkaloids KW - Azomethine ylides KW - Cycloaddition KW - Natural products KW - Ylides AB -

Vicinal quaternary and tertiary stereocenters of the 5,10b-phenanthridine skeleton 1 are constructed simultaneously in one step by the [3+2]-cycloaddition of non-stabilized azomethine ylide 9, generated by sequential double desilylation of 10 utilizing silver(I) fluoride as a one-electron oxidant. The regioas well as stereochemical origin of this cycloaddition reaction is explained through a favorable transition state 9''. The strategy is successfully applied for the total synthesis of the biologically active alkaloids (+/-)-maritidine (1a), (+/-)-crinine (1b), and their analogues (1d, 1e, and 1f).

PB - WILEY-V C H VERLAG GMBH CY - PO BOX 10 11 61, D-69451 WEINHEIM, GERMANY IS - 4 U3 - Foreign U4 - 3.07 ER -