Impact of peripheral substituents in regioselective synthesis of position-10 or position-20 bromo-bacteriochlorins

Autor: Shunichi Fukuzumi, Kei Ohkubo, Steve Zador, Walter A. Tabaczynski, Nayan J. Patel, Joseph R. Missert, Mykhaylo Dukh, Ravindra K. Pandey, Penny Joshi
Rok vydání: 2017
Předmět:
Zdroj: Tetrahedron Letters. 58:851-854
ISSN: 0040-4039
Popis: Bacteriochlorins derived either from chlorophyll-a or bacteriochlorophyll-a on reacting with pyridinium bromide or N-bromosuccinimide (NBS) gave the corresponding 10- or 20-bromo analogues. In contrast to methyl bacteriopyropheophorbide-a, which afforded 10-bromo derivative, the 7-keto and 8-ketobacteriochlorins under similar reaction conditions gave the corresponding 20-bromo analogues exclusively. In both series, the nature of substituents present at position-3 did not make any difference in the reaction outcome. Density functional calculations were carried out to clarify the difference in reactions outcome. Density functional calculations were carried out to clarify the difference in reactivity of bromination at 10- and 20- meso positions.
Databáze: OpenAIRE