Shengkun Li

The main chemical composition and in vitro antifungal activity of the essential oils of Ocimum basilicum Linn. var. pilosum (Willd.) Benth.

The essential oils of the aerial parts of Ocimum basilicum Linn. var. pilosum (Willd.) Benth., an endemic medicinal plant growing in China, was obtained by hydrodistillation and analysed by GC-MS. Fifteen compounds, representing 74.19% of the total oil were identified. The main components were as follows: linalool (29.68%), (Z)-cinnamic acid methyl ester (21.49%), cyclohexene (4.41%), α- cadinol (3.99%), 2,4-diisopropenyl-1-methyl-1-vinylcyclohexane (2.27%), 3,5-pyridine-dicarboxylic acid, 2,6-dimethyl-diethyl ester (2.01%), β-cubebene (1.97%), guaia-1(10),11-diene (1.58%), cadinene (1.41%) (E)-cinnamic acid methyl ester (1.36%) and β-guaiene (1.30%). The essential oils showed significant antifungal activity against some plant pathogenic fungi.

Highly Enantioselective Hydrogenation of β,β‐Disubstituted Nitroalkenes

Building the building blocks: A highly enantioselective hydrogenation of β-aryl-β-alkyl disubstituted nitroalkenes 1 has been developed. This method results in enantiomerically pure nitroalkanes 2, which are versatile precursors for chemical synthesis.

Highly Regioselective Isomerization–Hydroaminomethylation of Internal Olefins Catalyzed by Rh Complex with Tetrabi-Type Phosphorus Ligands

A highly regioselective isomerization-hydroaminomethylation of internal olefins has been developed. A 95.3% amine selectivity and 36.2 n/i ratio were obtained for 2-octene with a Tetrabi ligand and Rh(acac)(CO)(2), and a TON of linear amine was achieved of 6837 with a 39.1 n/i ratio of amine. The m-CF(3)-Ph substituted ligand was the best of the applied Tetrabi-type phosphorus ligands for different internal olefins, as up to a 99.2% amine selectivity and 95.6 n/i ratio were obtained for 2-pentene.

Synthesis of 1-Acyl-3-isopropenylbenzimidazolone Derivatives and Their Activity against Botrytis cinerea†

A series of 1-acyl-3-isopropenylbenzimidazolone derivatives were synthesized, and their structures were characterized by (1)H and (13)C NMR and elemental analysis. Their fungicidal activities against Botrytis cinerea were also evaluated by spore germination assay. The acrylic acid, methacrylic acid, 4-chlorophenyl acetic acid, and 2-chlorobenzoic acid derivatives exhibited strong fungicidal activity. This implied that benzimidazolones might be potential fungicide leading compounds.

Cascade Synthesis of Fenpiprane and Related Pharmaceuticals via Rhodium-Catalyzed Hydroaminomethylation

A novel rhodium catalytic system with Naphos as ligand was developed for an efficient hydroaminomethylation of 1,1-diphenylethene under relatively mild conditions. This will allow for an atom-economic and environmentally benign synthesis of fenpiprane and related pharmaceuticals.

Rh‐Catalyzed Highly Enantioselective Hydrogenation of Nitroalkenes under Basic Conditions

Since the first report by Knowles, Horner et al. in 1968, catalytic asymmetric hydrogenation of alkenes has been one of the most powerful approaches to chiral compounds and great progress has been made. Among the different alkenes, the hydrogenation of b,b-disubstituted nitroalkenes is a challenging problem. The resulting b-chiral nitroalkane from this “synthetic chameleon” is a valuable synthetic scaffold. The nitro group serves as a masked functionality and can be easily transformed to amine, aldehyde, carboxylic acid, nitrile oxide, and denitrated compound. A variety of asymmetric syntheses of the bchiral nitroalkanes by starting from nitroalkenes have, therefore, been developed, such as biocatalytic reduction, metalor organocatalyzed transfer hydrogenations, and enantioselective conjugate additions. We envision that asymmetric hydrogenation will furnish an efficient and environmental benign approach to prepare these important chiral compounds. Recently, our group reported the first enantioselective hydrogenation of b,b-disubstituted nitroalkenes with a Rh/Josiphos catalytic system. A number of chiral ligands were scanned and only a few promising results were achieved, and the enantioselectivity for most substrates was lower than 95 % ee (ee=enantiomeric excess) It is highly desirable to develop a more convenient and highly enantioselective protocol. Herein, we would like to report a novel rhodium catalytic system under basic conditions for highly enantioselective hydrogenation of b,bdisubstituted nitroalkenes. We believe that a monohydride RhH is responsible for the high enantioselectivity under basic conditions and this new protocol is notable with several attractive features: 1) addition of base is necessary for achieving both high enantioselectivity and high activity, and up to>99 % ee can be obtained (Scheme 1); 2) a number of

Rhodium-Catalyzed Enantioselective Hydrogenation of Oxime Acetates

Rh-catalyzed enantioselective hydrogenation of oxime acetates was first reported, which afforded a new approach for chiral amine synthesis.

First Iridium-Catalyzed Highly Enantioselective Hydrogenation of β-Nitroacrylates

The first highly chemo- and enantioselective hydrogenation of β-nitroacrylates was accomplished with an iridium catalyst (Ir-4) with yields and enantioselectivities of up to 96% and 98% ee, respectively. The resulting α-chiral β-nitro propionates are attractive building blocks for the synthesis of chiral β(2)-amino acids, which are the core scaffolds of bioactive natural products, pharmaceuticals, and β-peptides.