TY - JOUR
T1 - Fiaud's Acid
T2 - A Brønsted Acid Catalyst for Enantioselective Friedel-Crafts Alkylation of Indoles with 2-Alkene-1,4-diones
AU - Chatterjee, Sourav
AU - Hintermann, Lukas
AU - Mandal, Madhumita
AU - Achari, Anushree
AU - Gupta, Sreya
AU - Jaisankar, Parasuraman
N1 - Publisher Copyright:
© 2017 American Chemical Society.
PY - 2017/7/7
Y1 - 2017/7/7
N2 - Fiaud's acid (trans-1-hydroxy-2,5-diphenylphospholane 1-oxide), a phospholane-based phosphinic acid, is introduced as an efficient chiral Brønsted acid catalyst that mediates the asymmetric Friedel-Crafts alkylation of indoles with 2-butene-1,4-diones. With a catalyst loading of 10 mol %, the reaction proceeded smoothly to afford 2-(indol-3-yl)butane-1,4-diones in high yield (up to 82%) and high enantioselectivity (up to 91% ee, one such product showed enhanced ee of 98% after recrystallization). The reaction conditions are sufficiently mild to tolerate sensitive functionality at room temperature and are therefore suitable for the synthesis of complex targets.
AB - Fiaud's acid (trans-1-hydroxy-2,5-diphenylphospholane 1-oxide), a phospholane-based phosphinic acid, is introduced as an efficient chiral Brønsted acid catalyst that mediates the asymmetric Friedel-Crafts alkylation of indoles with 2-butene-1,4-diones. With a catalyst loading of 10 mol %, the reaction proceeded smoothly to afford 2-(indol-3-yl)butane-1,4-diones in high yield (up to 82%) and high enantioselectivity (up to 91% ee, one such product showed enhanced ee of 98% after recrystallization). The reaction conditions are sufficiently mild to tolerate sensitive functionality at room temperature and are therefore suitable for the synthesis of complex targets.
UR - http://www.scopus.com/inward/record.url?scp=85022199729&partnerID=8YFLogxK
U2 - 10.1021/acs.orglett.7b01383
DO - 10.1021/acs.orglett.7b01383
M3 - Article
C2 - 28609100
AN - SCOPUS:85022199729
SN - 1523-7060
VL - 19
SP - 3426
EP - 3429
JO - Organic Letters
JF - Organic Letters
IS - 13
ER -