Lian-Mei Chen

Enantioselective [4 + 2] Cycloaddition of Cyclic N-Sulfimines and Acyclic Enones or Ynones: A Concise Route to Sulfamidate-Fused 2,6-Disubstituted Piperidin-4-ones

A concise route to valuable sulfamate-fused 2,6-disubstituted piperidin-4-ones or 2,3-dihydropyridin-4(1H)-ones in good yield with high diastereo- and enantioselectivity is presented. The combination of chiral primary amine and o-fluorobenzoic acid efficiently promoted an asymmetric [4 + 2] cycloaddition reaction of N-sulfonylimines and enones or ynones. The cycloaddition reaction between cyclic N-sulfonylimines and ynones is first reported.

Metal‐Free Ring‐Expansion Reaction of Six‐membered Sulfonylimines with Diazomethanes: An Approach toward Seven‐Membered Enesulfonamides

A new metal-free, ring-expansion reaction of six-membered N-sulfonylimines with unstable diazomethanes, generated in situ from the N-tosylhydrazones, has been developed. This reaction delivers valuable seven-membered enesulfonamides by a Tiffeneau-Demjanov rearrangement and intramolecular proton transfer tautomerization process. Moreover, this ring-expansion reaction can be carried out in a one-pot fashion and scaled up to the gram scale by using aryl aldehydes, without the need to isolate the N-tosylhydrazone.

One-Pot Synthesis of Optically Enriched 2-Piperidinones from Aliphatic Aldehydes and Cyanoacrylamides

A highly stereoselective one-pot reaction of aliphatic aldehydes and cyanoacrylamides has been developed. The one-pot reaction includes an organocatalytic Michael addition followed by an intramolecular hemiaminalization. After reduction, optically enriched 2-piperidinones with three contiguous chiral centers were obtained in up to 95% yield and 9:1 dr with 99% ee.

(E)-2-(1,3-Diphenyl-allyl-idene)malononitrile.

The title compound, C18H12N2, adopts an E conformation with the benzylidenemalononitrile and phenyl groups located on opposite sides of the C=C bond. The two phenyl rings are oriented at a dihedral angle of 62.49 (7)°.

(E)-N-Benzyl-2-cyano-3-phenyl­acryl­amide

In the title compound, C17H14N2O, the N-benzylformamide and phenyl groups are located on the opposite sides of the C=C bond, showing an E configuration; the terminal phenyl rings are twisted to each other at a dihedral angle of 63.61 (7)°. Intermolecular classical N—H⋯N and weak C—H⋯O hydrogen bonds occur in the crystal structure.

2-[(E)-1-(4-Meth-oxy-phen-yl)pent-1-en-3-yl-idene]malononitrile.

In the title compound, C15H14N2O, the molecule skeleton displays an approximately planar structure except for the ethyl group [maximum deviation = 0.042 (1) Å]. The methoxyphenyl ring and butanylidenemalononitrile groups are located on opposite sides of the C=C bond, showing an E configuration. Weak intermolecular C—H⋯N hydrogen bonding is present in the crystal structure.

3-(3-Bromo­phen­yl)-N-phenyl­oxirane-2-carboxamide

There are two independent molecules in the asymmetric unit of the title compound, C15H12BrNO2. In both molecules, the two benzene rings adopt a cis configuration with respect to the epoxy ring. In one molecule, the epoxy ring makes dihedral angles of 60.5 (2) and 77.92 (19)° with the two benzene rings; in the other molecule, the values are 61.0 (2) and 81.43 (19)°. Intermolecular N—H⋯O and C—H⋯O hydrogen bonding is present in the crystal structure.

Trimethyl 5-(2-chloro-4-fluoro­phen­yl)-2-phenyl­pyrrolidine-2,3,4-tricarboxyl­ate

The title compound, C22H21ClFNO6, was synthesized by the 1,3-dipolar cycloaddition reaction of dimethyl maleate, methyl 2-amino-2-phenylacetate and 2-chloro-4-fluorobenzaldehyde. The pyrrolidine ring possesses an envelope conformation and the two benzene rings are oriented at a dihedral angle of 68.28 (7)°. Weak intermolecular C—H⋯O hydrogen bonding is present in the crystal structure. One methyl group is disordered over two positions with a site-occupancy ratio of 0.651 (12):0.349 (12).

2-(7-Methyl-3-oxo-1-phenyl-perhydro-naphthalen-4a-yl)malononitrile.

In the title compound, C20H22N2O, both cyclohexane rings adopt chair conformations. Weak C—H⋯N and C—H⋯O hydrogen bonding is present in the crystal structure.

3-(1-Naphth­yl)-N-phenyl­oxirane-2-carboxamide

In the title compound, C19H15NO2, the molecule adopts a syn configuration with the naphthalene and N-phenylformamide units located on the same side of the epoxy ring. The epoxy ring makes dihedral angles of 58.73 (9) and 65.18 (9)°, respectively, with the naphthalene ring system and the benzene ring. Intermolecular N—H⋯O and C—H⋯O hydrogen bonding is present in the crystal structure.