Novel thiophosphonodiamides as efficient hydrogen bond donor catalysts in tandem Michael addition–cyclization of malononitrile and 2-(E)-2-nitrovinylphenols
摘要:
From L-amino acid, three chiral thiophosphonodiamides were prepared as new hydrogen bond donor organocatalysts. Under the mediation of the catalyst derived from L-valine, a tandem Michael addition/cyclization reaction between (E)-2-(2-nitrovinyl)phenols and malononitrile proceeds smoothly, giving pharmaceutically valuable 2-amino-4H-chromene-3-carbonitriles in high yields with 66-95% ee within 2 h. (C) 2013 Elsevier Ltd. All rights reserved.
Enantioselective Synthesis of Quaternary α-Amino Acids via <scp>l</scp>-<i>tert</i>-Leucine-Derived Squaramide-Catalyzed Conjugate Addition of α-Nitrocarboxylates to Enones
作者:Kalisankar Bera、Nishikant S. Satam、Irishi N. N. Namboothiri
DOI:10.1021/acs.joc.6b00543
日期:2016.7.1
Enantioselective Michael addition of tertiary α-nitroesters to β-unsubstituted vinyl ketones has been carried out in the presence of an l-tert-leucine-derived squaramide as organocatalyst. The products, quaternary α-nitroesters, were formed in excellent yield and moderate to good ee’s in most cases. Scale-up of the reaction and synthetic applications of the products, including transformation to representative
Synthesis and antimalarial activity of new 4-aminoquinolines active against drug resistant strains
作者:Srinivasarao Kondaparla、Awakash Soni、Ashan Manhas、Kumkum Srivastava、Sunil K. Puri、S. B. Katti
DOI:10.1039/c6ra14016e
日期:——
containing basic tertiary terminal nitrogen and bioevaluated them for antimalarial activity against Plasmodium falciparum in vitro (CQ-sensitive strain-3D7 & CQ-resistant strain-K1) and Plasmodium yoelii in vivo (N-67 strain). Among the series, thirteen compounds showed superior antimalarial activity against K1 strain as compared to CQ. In addition, all these analogs showed 100% suppression of parasitaemia
The first enantioselective Michael addition of alpha-cyanoketones to alpha,beta-unsaturated trifluoromethyl ketones using a novel piperazine-thiourea catalyst was described. The resulting alpha-trifluoromethyldihydropyrans were obtained in high yields and with up to 95% ee within a short reaction time. A useful transformation of the chiral adduct was also illustrated.
The first primary aminocatalytic direct cross-aldol reaction of acetaldehyde is presented. Among the various vicinal diamines screened, the L-tert-leucine derivative 1c in conjunction with (H4SiW12O40)0.25 was identified as the optimal catalyst; good catalytic activity (up to 99 % yield in 4 h), and high enantioselectivities (up to 92 % ee) were achieved for a range of donors, including aromatic aldehydes
Enantioselective conjugate addition of pyrazolones to nitroalkenes catalyzed by chiral squaramide organocatalyst
作者:Alime Ebru Aydin、Selda Culha
DOI:10.1002/chir.23295
日期:2021.3
squaramide catalysts (8–15) were synthesized, and their catalytic efficiency in the enantioselectiveconjugateaddition of pyrazolones to nitroalkenes was described. This protocol provides excellent chemical yields (up to 93%) of chiral 5‐methyl‐4‐(2‐nitro‐1‐arylethyl)pyrazol‐3‐ol derivatives with high enantioselectivities (up to 97% ee).