Asymmetric Total Synthesis of Batzelladine D: Molecule 18 to Molecule 23

Cohen, F.; Overman, L. E.; Ly Sakata, S. K. Org. Lett. 1999, 1, 2169-2172.

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This paper explores batzelladines, a class of polyguanidine alkaloids found in the Caribbean sponge Batzella (see pictures). Batzelladines are structures that are studied extensively due to the importance of ligands which regulate protein association. In addition, batzelladines have the potential as an anti HIV compound, making them very important to society. Particularly, the researchers modified a tethered Biginelli strategy to prepare (–)-batzelladine D from the same chemistry used to make enantiopure anti octahydro-5,6,8b-triazaacenaphthalenes. The researchers’ aims were to construct batzelladine D from iminopyrrolopyrimidine which would come as a result of a Biginelli condensation of acetoacetate and guanidine aldehyde. In this specific step, molecule 18 reacts with rhodium on dialuminum trioxide through hydrogenation and deprotection of Cbz to form molecule 23.