Sclerotigenin

Natural products sclerotigenin, pegamine, deoxyvasicinone, mackinazolinone, and rutaecarpine were synthesized. Core quinazolinone structures were constructed via Ir catalysis.

A fluorous linker-assisted synthetic protocol has been developed for preparation of sclerotigenin-type benzodiazepine-quinazolinone library containing 144 analogues. Amide coupling of fluorous trimethoxybenzyl (TMB)-protected amino esters with anthranilic acids followed by base-promoted cyclizations afforded 4-benzodiazepine-2,5-diones. Further derivatization of benzodiazepinediones by reacting with azidobenzoyl chlorides, cyclization, and fluorous linker cleavage afforded the desired compound library. The reaction intermediates were purified by fluorous solid-phase extraction (F-SPE) and final products were further purified by prep-HPLC.

Raistrickindole A (1), a new indole diketopiperazine alkaloid containing an unusual pyrazino[1',2':2,3][1,2]oxazino[6,5- b]indole tetraheterocyclic ring system, a new benzodiazepine derivative, raistrickin (2), and the known haenamindole (3) and sclerotigenin (4) were isolated from the marine-derived fungus Penicillium raistrickii IMB17-034. Their structures were elucidated by extensive spectroscopic analyses and TDDFT calculations of the NMR and ECD data. Compounds 1 and 2 showed inhibitory activities against the hepatitis C virus.