Copper-catalyzed reactions of α,ß-unsaturated N-tosylhydrazones with diaryliodonium salts to construct N-arylpyrazoles and diaryl sulfones.

Herein, an economical copper-catalyzed reaction of α,ß-unsaturated N-tosylhydrazones with diaryliodonium salts to construct both N-arylpyrazoles and diaryl sulfones has been developed. Both the p-toluenesulfonyl anion and the 3-arylpyrazole intermediates were formed in situ from N-tosylhydrazones. Subsequently, the former reacted rapidly with diaryliodonium salts to give diaryl sulfones and aryl iodide intermediates, and the latter reacted with aryl iodide to give N-arylpyrazoles under copper-catalyzed conditions. Using unsymmetrical mesityl phenyliodonium salts as substrates, mesityl p-toluenesulfide was obtained as the major product. This reaction took full advantage of the "waste" part of substrates to form an extra diaryl sulfone.

Synthesis, Characterization of Spirocyclic λ3 -Iodanes and Their Application to Prepare 4,1-Benzoxazepine-2,5-diones and 1,3-Diynes.

Herein, a [3+2] cycloaddition of aza-oxyallylic cations with ethynylbenziodoxolones for synthesis of new λ3 -iodanes containing spirocyclic 4-oxazolidinone has been developed. This cyclic λ3 -iodanes display stability in air and excellent solubility in organic solvent. Using them as substrate, both the 4,1-benzoxazepine-2,5-diones and symmetrical 1,3-diynes derivatives were afforded in high yield under copper(I)-catalyzed conditions.

A base-promoted cascade reaction of α,ß-unsaturated N-tosylhydrazones with o-hydroxybenzyl alcohols: highly regioselective synthesis of N-sec-alkylpyrazoles.

An efficient method for the synthesis of N-sec-alkylpyrazoles through a base-promoted cascade cyclization/Michael addition reaction of α,ß-unsaturated N-tosylhydrazones with ortho-hydroxybenzyl alcohols has been developed. The desired products containing di- or triaryl groups at the same carbon atom were afforded in good to excellent yields with excellent regioselectivities (>20 : 1). Moreover, a three-component reaction of ortho-hydroxybenzyl alcohols, α,ß-unsaturated N-tosylhydrazones and saturated N-tosylhydrazones also took place to afford pyrazoles in good yields. This reaction offers a new route to triarylmethanes with a simple operation and is applicable for large-scale synthesis.

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.

Enantio- and Diastereoselective Formal Hetero-Diels-Alder Reactions of Trifluoromethylated Enones Catalyzed by Chiral Primary Amines.

Enantioselective formal hetero-Diels-Alder reactions of trifluoromethylated enones and 2-amino-1,3-butadienes generated in situ from aliphatic acyclic enones and chiral primary amines are reported. The corresponding tetrahydropyran-4-ones are formed in up to 94 % yield and with up to 94 % ee. The reaction was carried out through a stepwise mechanism, including initial aminocatalytic aldol condensation of 2-amino-1,3-butadiene to the trifluoromethylated carbonyl group followed by an intramolecular oxa-Michael addition. Both NMR investigation and theoretical calculations on the transition state indicate that the protonated tertiary amine could effectively activate the carbonyl group of the trifluoromethyl ketone to promote the addition process through hydrogen-bonding interaction of N-H⋅⋅⋅F and N-H⋅⋅⋅O simultaneously, and thus provide a chiral environment for the approach of amino-1,3-butadienes to the activated trifluoromethyl ketone, resulting in high enantioselectivity.

Palladium-catalyzed asymmetric cycloadditions of vinylcyclopropanes and in situ formed unsaturated imines: construction of structurally and optically enriched spiroindolenines.

A palladium-catalyzed (3 + 2) cycloaddition of vinyl cyclopropane and α,ß-unsaturated imines generated in situ from aryl sulfonyl indoles is reported. The reaction proceeds with high diastereoselectivity to provide the optically enriched spirocyclopentane-1,3'-indolenines in up to 74% yield and with up to 97% ee, which contains an all-carbon quaternary center and two tertiary stereocenters. The reaction involves a first conjugate addition of the carbon anion of zwitterionic π-allylpalladium complex from vinyl cyclopropane to the in situ formed unsaturated imine followed by a palladium-catalyzed intramolecular C3-allylation of indole.

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.

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.

Highly enantioselective aldol reactions between acetaldehyde and activated acyclic ketones catalyzed by chiral primary amines.

Highly enantioselective cross-aldol reactions between acetaldehyde and activated acyclic ketones are reported for the first time. Various acyclic ketones, such as saturated and unsaturated keto esters, reacted with acetaldehyde in the presence of a chiral primary amine and a Brønsted acid to afford optically enriched tertiary alcohols in good yields and with excellent enantioselectivities. Trifluoromethyl ketones were tolerable under the reaction conditions, thereby affording the trifluoromethyl carbinol in good-to-excellent yields and enantioselectivities. Structural modification of the chiral amines from the same chiral source switched the stereoselectivity of the products. The utility of aldol chemistry was demonstrated in the brief synthesis of functionally enriched δ-lactones. Theoretical calculations on the transition-state structure indicated that the protonated tertiary amine could effectively activate the carbonyl group of a keto ester to promote the addition process through hydrogen-bonding interaction and, simultaneously, provide an appropriate attacking pattern for the approach of the keto ester to the enamine, which is formed from acetaldehyde and the chiral catalyst, on a particular face, resulting in high enantioselectivity.

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

The title mol-ecule, C(14)H(11)FN(2), is approximately planar except the ethyl group, the maximum atomic deviation being 0.105 (5) Å. The fluoro-phenyl ring and 2-propyl-idene-malononitrile unit are located on the opposite sides of the C=C double bond, showing an E configuration.

(E)-2-[4-(2-Chloro-phen-yl)but-3-en-2-yl-idene]malononitrile.

There are two independent but virtually identical mol-ecules in the asymmetric unit of the title compound, C(13)H(19)ClN(2). Each mol-ecular skeleton displays an approximately planar structure except for the methyl group [the r.m.s. deviations for all 16 non-H atoms are 0.039 (mol-ecule 1) and 0.056 Š(mol-ecule 2)]. An E configuration is found about each of the C=C bonds. The crystal packing is stabilized by C-H⋯N inter-actions that connect the independent mol-ecules into supra-molecular chains along the c-axis direction.

Diastereoselective and enantioselective capture of chiral zinc enolate using nitroolefins: a rapid access to chiral γ-nitro carbonyl compounds.

Highly diastereoselective and enantioselective catalytic capture of chiral zinc enolates using nitroolefins as electrophiles is described. The tandem products γ-nitro ketones were obtained in good yields with high diastereoselectivities and enantioselectivities. The γ-nitro ketones were readily hydrogenated to the optically enriched and diastereomerically pure chiral pyrrolidines with four contiguous stereocentres under mild conditions.

3-(3-Cyano-phen-yl)-N-phenyl-oxirane-2-carboxamide.

In the title compound, C(16)H(12)N(2)O(2), both terminal benzene rings are located at the same side of the central epoxide ring, showing a cis conformation. The epoxide ring makes dihedral angles of 76.59 (10) and 62.40 (11)° with the phenyl and cyano-phenyl rings, respectively. Inter-molecular N-H⋯O and weak C-H⋯O hydrogen bonding is present in the crystal structure.

(E)-N-Benzyl-2-cyano-3-phenyl-acryl-amide.

In the title compound, C(17)H(14)N(2)O, the N-benzyl-formamide 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)°. Inter-molecular 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, C(15)H(14)N(2)O, the mol-ecule skeleton displays an approximately planar structure except for the ethyl group [maximum deviation = 0.042 (1) Å]. The meth-oxy-phenyl ring and butanylidenemalononitrile groups are located on opposite sides of the C=C bond, showing an E configuration. Weak inter-molecular C-H⋯N hydrogen bonding is present in the crystal structure.

2-[(E)-4-(2-Bromo-phen-yl)but-3-en-2-yl-idene]malononitrile.

The title compound, C(13)H(19)BrN(2), is planar structure except for the methyl H atoms, the maximum atomic deviation for the non-H atoms being 0.100 (1) Å. The bromo-phenyl and isopropanylidenemalononitrile units are located on opposite sides of the C=C bond, showing an E configuration.

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

In the title compound, C(20)H(22)N(2)O, both cyclo-hexane rings adopt chair conformations. Weak C-H⋯N and C-H⋯O hydrogen bonding is present in the crystal structure.

(2R,3R)-3-(2-Chloro-phen-yl)-N-phenyl-oxirane-2-carboxamide.

In the title compound, C(15)H(12)ClNO(2), the two benzene rings adopt a syn configuration with respect to the ep-oxy ring; the dihedral angles between the ep-oxy ring and the two benzene rings are 59.71 (16) and 67.58 (15)°. There is a weak intra-molecular N-H⋯O bond, which may help to establish the conformation. In the crystal, the mol-ecules are linked into a chain parallel to the b axis through inter-molecular N-H⋯O hydrogen bonds.

3-(1-Naphth-yl)-N-phenyl-oxirane-2-carboxamide.

In the title compound, C(19)H(15)NO(2), the mol-ecule adopts a syn configuration with the naphthalene and N-phenyl-formamide units located on the same side of the ep-oxy ring. The ep-oxy ring makes dihedral angles of 58.73 (9) and 65.18 (9)°, respectively, with the naphthalene ring system and the benzene ring. Inter-molecular N-H⋯O and C-H⋯O hydrogen bonding is present in the crystal structure.