941602-11-5Relevant articles and documents
Molecular Engineering of β-Substituted Oxoporphyrinogens for Hydrogen-Bond Donor Catalysis
Chahal, Mandeep K.,Payne, Daniel T.,Matsushita, Yoshitaka,Labuta, Jan,Ariga, Katsuhiko,Hill, Jonathan P.
, p. 82 - 90 (2020/01/02)
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.
A Recyclable Hydrophobic Anchor-Tagged Asymmetric Amino Thiourea Catalyst
Jichu, Takahisa,Inokuma, Tsubasa,Aihara, Keisuke,Kohiki, Taiki,Nishida, Kodai,Shigenaga, Akira,Yamada, Ken-ichi,Otaka, Akira
, p. 3402 - 3405 (2018/08/01)
A novel, recyclable, thiourea-based asymmetric organocatalyst containing a hydrophobic anchor has been developed. The chemical nature of the hydrophobic anchor contributes to the desirable characteristics of the recyclable catalyst. The hydrophobic anchor
Biodegradable Chitosan-Derived Thioureas as Recoverable Supported Organocatalysts – Application to the Stereoselective Aza-Henry Reaction
Andrés, José M.,González, Fernando,Maestro, Alicia,Pedrosa, Rafael,Valle, María
, p. 3658 - 3665 (2017/07/22)
Eight different biodegradable chitosan-supported bifunctional chiral thioureas have been prepared as a greener and more sustainable alternative to those supported on petrochemical-derived polymers. These organocatalysts promoted an enantioselective aza-He
