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Molecular Engineering of β‐Substituted Oxoporphyrinogens for Hydrogen‐Bond Donor Catalysis
Author(s) -
Chahal Mandeep K.,
Payne Daniel T.,
Matsushita Yoshitaka,
Labuta Jan,
Ariga Katsuhiko,
Hill Jonathan P.
Publication year - 2020
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/ejoc.201901706
Subject(s) - chemistry , intramolecular force , catalysis , hydrogen bond , bifunctional , combinatorial chemistry , low barrier hydrogen bond , conjugate , polymer chemistry , photochemistry , organic chemistry , molecule , mathematical analysis , mathematics
A new class of bifunctional hydrogen‐bond donor organocatalyst using oxoporphyrinogens having increased intramolecular hydrogen‐bond donor distances is reported. Oxoporphyrinogens are highly non‐planar rigid macrocycles containing a multiple hydrogen bond‐forming binding site. In this work, we describe the first example of non‐planar OxPs as hydrogen‐bond donor catalysts prepared using a molecular engineering approach of the binding site for dual activation of substrates. The introduction of β‐substituents is key to the catalytic activity and the catalysts are able to catalyze 1,4‐conjugate additions and sulfa‐Michael additions, as well as, Henry and aza‐Henry reactions at low catalyst loadings (≤ 1 mol‐%) under mild conditions. Preliminary mechanistic studies have been carried out and a possible reaction mechanism has been proposed based on the bi‐functional activation of both substrates through hydrogen‐bonding interactions.