We have found that Suzuki–Miyaura-type reactions of dibromoalkenes with arylboronic acids using a hydrazone–Cu catalyst system proceeded smoothly under mild conditions to afford the corresponding internal alkyne derivatives in good yields. Furthermore, we also succeeded in the synthesis of o-allyloxy(ethynyl)benzene derivatives, which are known to be effective precursors of various heterocyclic compounds, through this reaction.

Such chiral phosphine–internal olefin hybrid type ligands as N-1-adamantyl-N-cinnamylaniline derivatives 1 with C(aryl)–N(amine) bond axial chirality were synthesized and utilized for the palladium-catalyzed asymmetric allylic alkylation of indoles to afford the desired products in high enantioselectivities (up to 98% ee).

A chiral aluminum catalyst was used for the kinetic resolution of citronellal analogues. Racemic 3-alkylcitronellals gave optically active 5-alkylisopulegols with high enantioselectivity. Unreacted 3-alkylcitronellal analogues were obtained with low enantioselectivity. The two main diastereoisomers of the product were opposite to each other. The scents of 5-substituted isopulegols were evaluated. The chiral recognition of the catalysts and their effects on the kinetic resolutions are also discussed.

Annulation of 1-allyl-2-bromobenzene derivatives with internal alkynes using a hydrazone–palladium catalyst system proceeded smoothly and gave the corresponding polysubstituted naphthalene derivatives in good to high yields.

We report a highly selective asymmetric ring-closing ene reaction catalysed by aluminum complexes with chiral BINOL. This reaction yields optically active 6-membered cyclized alcohols from unsaturated aldehydes, with good diastereo- and enantioselectivities. Asymmetric amplification of this reaction was investigated by varying the ee of the BINOL employed in the catalyst.

Correction for ‘Highly selective aluminium-catalysed intramolecular Prins reaction for L-menthol synthesis’ by H. Itoh et al., RSC Adv., 2014, 4, 61619–61623.

Rhodium(I)-catalyzed asymmetric 1,4-addition of arylboronic acids 2 to coumarins 1 using (S)-BICMAP as a chiral ligand gave the desired 4-arylchroman-2-one derivatives 2 in good yields and with high enantioselectivities (up to 99% ee).(S)-4-Phenylchroman-2-oneC15H12O2ee = 99% from HPLC[α]D20 = +41.2 (c 0.62, CHCl3)Source of chirality: Asymmetric synthesisAbsolute configuration: (S)(S)-4-(4-Methylphenyl)chroman-2-oneC16H14O2ee = 98% from HPLC[α]D20 = +45.5 (c 0.45, CHCl3)Source of chirality: Asymmetric synthesisAbsolute configuration: (S)(S)-4-(4-Methoxyphenyl)chroman-2-oneC16H14O3ee = 95% from HPLC[α]D20 = +35.7 (c 0.51, CHCl3)Source of chirality: Asymmetric synthesisAbsolute configuration: (S)(S)-4-(3-Methylphenyl)chroman-2-oneC16H14O2ee = 95% from HPLC[α]D20 = +41.5 (c 0.50, CHCl3)Source of chirality: Asymmetric synthesisAbsolute configuration: (S)(S)-4-(3,5-Dimethylphenyl)chroman-2-oneC17H16O2ee = 99% from HPLC[α]D20 = +40.1 (c 0.40, CHCl3)Source of chirality: Asymmetric synthesisAbsolute configuration: (S)(S)-4-(2-Naphthalenyl)chroman-2-oneC19H14O2ee = 80% from HPLC[α]D20 = +42.6 (c 0.45, CHCl3)Source of chirality: Asymmetric synthesisAbsolute configuration: (S)(S)-4-(2-Methylphenyl)chroman-2-oneC16H14O2ee = 99% from HPLC[α]D20 = +75.5 (c 0.35, CHCl3)Source of chirality: Asymmetric synthesisAbsolute configuration: (S)(S)-6-Methyl-4-phenylchroman-2-oneC16H14O2ee = 96% from HPLC[α]D20 = +3.5 (c 0.51, CHCl3)Source of chirality: Asymmetric synthesisAbsolute configuration: (S)(S)-7-Methyl-4-phenylchroman-2-oneC16H14O2ee = 96% from HPLC[α]D20 = +33.4 (c 0.51, CHCl3)Source of chirality: Asymmetric synthesisAbsolute configuration: (S)(S)-7-Methoxy-4-phenylchroman-2-oneC16H14O2ee = 98% from HPLC[α]20D = +41.0 (c 0.37, CHCl3)Source of chirality: Asymmetric synthesisAbsolute configuration: (S)

We found that N-(tert-butyl)-N-methylanilines 1 have C(aryl)–N(amine) bond axial chirality and succeeded the optical resolution of C–N bond atropisomers of amines 1 by a chiral palladium resolving agent and/or a chiral HPLC method. Finally, we demonstrated the ability of chiral amines 1 as a ligand in palladium-catalyzed asymmetric allylic alkylation of allylic esters with malonates (up to 95% ee).

An aluminium complex bearing 2-cyclohexyl-6-phenylphenol afforded (5R)-n-isopulegol from (R)-citronellal via the intermolecular Prins reaction with an exceptionally high diastereoselectivity. Using this reaction, L-menthol was obtained with an excellent diastereoselectivity.

Palladium-catalyzed decarboxylative coupling of benzoic acid derivatives with arylboroxins gave biaryls using a catalytic amount of Pd(TFA)2–hydrazone 1d system with Ag2CO3 at 80 °C in good yields. We also found that decarboxylative coupling with aryl(trialkoxy)silanes gave biaryls using a Pd(TFA)2–hydrazone 1g system with AgF in good yields.

Allylic arylation of cinnamyloxyphenylboronic acid pinacol esters 3, which have arylboronic acid moiety and allylic ether moiety, using a hydrazone 1d–Pd(OAc)2 system proceeded and gave the corresponding 1,3-diarylpropene derivatives 4 with a phenolic hydroxyl group via a selective coupling reaction of the π-allyl intermediate to the boron-substituted position of the leaving group.

The copper-catalyzed asymmetric propargylic amination of propargylic acetates 1 with amines 2 using BICMAP as a chiral ligand gave the desired products 3 in good yields and with moderate to high enantioselectivities (up to 90% ee).(S)-(+)-N-Methyl-N-(1-phenyl-2-propynyl)anilineC16H15Nee = 87% from HPLC[α]D20=+6.2 (c 0.27, CHCl3)Souce of chirality: Asymmetric synthesisAbsolute configuration: (S)(S)-(−)-N-Methyl-N-[1-(4-methylphenyl)-2-propynyl]anilineC17H17Nee = 77% from HPLC[α]D20=-1.4 (c 0.50, CHCl3)Souce of chirality: Asymmetric synthesisAbsolute configuration: (S)(S)-(−)-N-Methyl-N-[1-(4-chlorophenyl)-2-propynyl]anilineC16H14ClNee = 87% from HPLC[α]D20=-12.1 (c 0.49, CHCl3)Souce of chirality: Asymmetric synthesisAbsolute configuration: (S)(S)-(−)-N-Methyl-N-[1-(4-methoxyphenyl)-2-propynyl]anilineC17H17NOee = 37% from HPLC[α]D20=-8.0 (c 0.25, CHCl3)Souce of chirality: Asymmetric synthesisAbsolute configuration: (S)(S)-(+)-N-Methyl-N-[1-(2-methylphenyl)-2-propynyl]anilineC17H17Nee = 81% from HPLC[α]D20=+41.2 (c 0.25, CHCl3)Souce of chirality: Asymmetric synthesisAbsolute configuration: (S)(S)-(−)-N-Methyl-N-[1-(naphthalen-2-yl)-2-propynyl]anilineC20H17Nee = 72% from HPLC[α]D20=-7.1 (c 0.81, CHCl3)Souce of chirality: Asymmetric synthesisAbsolute configuration: (S)(S)-(+)-N-Methyl-N-(1-phenyl-2-propynyl)-p-methylanilineC17H17Nee = 83% from HPLC[α]D20=+16.8 (c 0.25, CHCl3)Souce of chirality: Asymmetric synthesisAbsolute configuration: (S)(S)-(+)-N-Methyl-N-(1-phenyl-2-propynyl)-p-methoxyanilineC17H17NOee = 79% from HPLC[α]D20=+12.7 (c 0.52, CHCl3)Souce of chirality: Asymmetric synthesisAbsolute configuration: (S)(S)-(+)-N-Methyl-N-(1-phenyl-2-propynyl)-p-chloroanilineC16H14ClNee = 90% from HPLC[α]D20=+3.3 (c 0.28, CHCl3)Souce of chirality: Asymmetric synthesisAbsolute configuration: (S)(S)-(−)-N-Ethyl-N-(1-phenyl-2-propynyl)-p-chloroanilineC17H16ClNee = 88% from HPLC[α]D20=-27.1 (c 0.22, CHCl3)Souce of chirality: Asymmetric synthesisAbsolute configuration: (S)(S)-(−)-N-Ethyl-N-(1-phenyl-2-propynyl)anilineC17H17Nee = 82% from HPLC[α]D20=-13.8 (c 0.31, CHCl3)Souce of chirality: Asymmetric synthesisAbsolute configuration: (S)(S)-(+)-N-(1-Phenyl-2-propynyl)anilineC15H13Nee = 44% from HPLC[α]D20=+33.3 (c 0.27, CHCl3)Souce of chirality: Asymmetric synthesisAbsolute configuration: (S)(S)-(+)-N-Methyl-N-(1-phenyl-2-propynyl)indolineC17H15Nee = 70% from HPLC[α]D20=+54.3 (c 0.23, CHCl3)Souce of chirality: Asymmetric synthesisAbsolute configuration: (S)

The palladium-catalyzed asymmetric allylic alkylation of indoles with 1,3-diphenyl-2-propenyl acetate using P/N-type ligands such as N-aryl indole, C–N bond axially chiral aminophosphine (aS)-L4, gave the desired products 1 in good yields and with moderate to high enantioselectivities (up to 90% ee).(R)-(–)-3-[(E)-1,3-Diphenyl-2-propen-1-yl]-6-methyl-1H-indoleC24H21Nee = 33% from HPLC[α]D20 = –13.2 (c 0.50, CHCl3)Source of chirality: asymmetric synthesisAbsolute configuration: (R)(R)-(–)-3-[(E)-1,3-Diphenyl-2-propen-1-yl]-6-methoxy-1H-indoleC24H21NOee = 75% from HPLC[α]D20 = –37.0 (c 0.50, CHCl3)Source of chirality: asymmetric synthesisAbsolute configuration: (R)(R)-(–)-6-Benzyoxy-3-[(E)-1,3-diphenyl-2-propen-1-yl]-1H-indoleC30H25NOee = 34% from HPLC[α]D20 = –11.6 (c 0.50, CHCl3)Source of chirality: asymmetric synthesisAbsolute configuration: (R)(R)-(–)-6-Chloro-3-[(E)-1,3-diphenyl-2-propen-1-yl]-1H-indoleC23H18ClNee = 86% from HPLC[α]D20 = –13.3 (c 0.50, CHCl3)Source of chirality: asymmetric synthesisAbsolute configuration: (R)(R)-(–)-6-Fluoro-3-[(E)-1,3-diphenyl-2-propen-1-yl]-1H-indoleC23H18FNee = 44% from HPLC[α]D20 = –14.2 (c 0.50, CHCl3)Source of chirality: asymmetric synthesisAbsolute configuration: (R)

Chiral dihydrobenzofuran-based diphosphine ligand (BICMAP) 1 was used as a ligand for the rhodium(I)-catalyzed asymmetric 1,4-addition of arylboronic acids to cyclic enones up to 99% ee. We also found that the BICMAP-rhodium system was an efficient catalyst for the 1,4-addition of alkenylboronic acids to 2-cyclohexenone in good enantioselectivities.

Chiral phosphine-prolineamide 1a was employed as an organocatalyst in direct asymmetric aldol reactions of various aromatic aldehydes with ketones. Cyclohexanone led to the aldol products in up to 98% ee and with good diastereoselectivity using 10 mol % of TFA and 30 mol % of prolineamide 1a in DMF at 0 °C.(S)-N-(2-Diphenylphosphinophenyl)pyrrolidine-2-carboxamideC23H23N2OP[α]D25=-39.3 (c 0.30, CHCl3)Source of chirality: l-(−)-prolineAbsolute configuration: (S)(S)-N-(2-Diphenylphosphorylphenyl)pyrrolidine-2-carboxamideC23H23N2O2P[α]D25=+36.8 (c 0.30, CHCl3)Source of chirality: l-(−)-prolineAbsolute configuration: (S)

N-Aryl indole-derived C–N bond axially chiral phosphine ligands 2a–c were obtained by DDQ oxidation of N-aryl indoline-derived phosphine oxide followed by silane reduction. Resolution of C–N bond atropisomers was achieved by chiral HPLC. The investigation of the rotation barrier for the C–N bond axial stability of phosphines and the determination of the absolute configuration of 2c are described. Finally, the ability of the chiral ligand 2c was demonstrated in a palladium-catalyzed asymmetric allylic alkylation (up to 99% ee).(−)-N-(2-Diphenylphosphino-6-methoxyphenyl)indoleC27H22NOPEe ⩾ 99% (chiral HPLC)[α]D20=-55.4 (c 0.25, CHCl3)Source of chirality: resolution by HPLC(−)-N-(2-Diphenylphosphino-6-methylphenyl)indoleC27H22NPEe ⩾ 99% (chiral HPLC)[α]D25=-125.0 (c 0.50, CHCl3)Source of chirality: resolution by HPLC(R)-(−)-N-(2-Diphenylphosphino-6-trifluoromethylphenyl)indoleC27H19NF3PEe ⩾ 99% (chiral HPLC)[α]D20=-183.4 (c 0.20, CHCl3)Source of chirality: resolution by HPLCAbsolute configuration: (R)(−)-2-Diphenylphosphino-1-(o-tolyl)indoleC27H22NPEe ⩾ 99% (chiral HPLC)[α]D25=-2.5 (c 1.00, CHCl3)Source of chirality: resolution by HPLC

Chiral allylic esters, such as (R)-1,3-diphenyl-2-propenyl acetate (R)-2a, were synthesized by kinetic resolution in a palladium-catalyzed asymmetric allylic alkylation using N-aryl indoline type C–N bond axially chiral aminophosphines (S)-1 as ligands.(R)-1,3-Diphenylprop-2-en-1-yl acetateC17H16O2Ee = 95% (chiral HPLC)[α]D20=-4.9 (c 0.30, CHCl3)Source of chirality: asymmetric synthesisAbsolute configuration: (R)(R)-1,3-Diphenylprop-2-en-1-yl pivalateC20H22O2Ee = 55% (chiral HPLC)[α]D20=+3.4 (c 0.35, CHCl3)Source of chirality: asymmetric synthesisAbsolute configuration: (R)(R)-1,3-Diphenylprop-2-en-1-yl benzoateC22H18O2Ee = 59% (chiral HPLC)[α]D20=+8.0 (c 0.30, CHCl3)Source of chirality: asymmetric synthesisAbsolute configuration: (R)

Palladium-catalyzed asymmetric allylic alkylation of 1,3-diphenyl-2-propenyl acetate (4) with a dimethyl malonate–BSA–LiOAc system has been successfully carried out in the presence of chiral phosphine–hydrazone ligands such as 3a in good yields with good enantioselectivities (up to 84% ee).Chiral phosphine–hydrazones 3 were easily prepared from 1′-(diphenylphosphino)-1-ferrocenecarboxaldehyde with chiral hydradines. Palladium-catalyzed asymmetric allylic alkylation of 1,3-diphenyl-2-propenyl acetate (4) with a various malonate–BSA–LiOAc system has been successfully carried out in the presence of 3a in good yields with good enantioselectivities (up to 84% ee).

The existence of 3 as a pair of stable atropisomers has been demonstrated analytically through chiral phase LC–CD investigations. Resolution of 3d was achieved by preparative chiral HPLC. Finally, the ability of the first C(aryl)N(amine) axially chiral phosphine ligand 3d is demonstrated in a catalytic asymmetric reaction.Graphic(−)-1-[2′-(Diphenylphospino)-6′-methylphenyl]-2,3-dihydro-1H-indoleC27H24NPE.e.=99% [by HPLC on Chiralcel OJ][α]D25=−19.2 (c 0.27, CHCl3)Source of chirality: HPLC resolution

Annulation of 1-allyl-2-bromobenzene derivatives with internal alkynes using a hydrazone–palladium catalyst system proceeded smoothly and gave the corresponding polysubstituted naphthalene derivatives in good to high yields.

A highly reactive catalytic ring-closing ene reaction is discussed. This reaction is catalyzed via novel optically active aluminum BINOL and TADDOL complexes. The kinetic resolution of the racemic analogs of citronellal was affected by these Al catalysts. The BINOL-Al catalyst afforded 68% ee of a diastereomer of isopulegol and 62% ee of citronellal at 47% conversion. The reaction mechanism proposed assumes that the optically active catalyst possesses a metal center between two parallel aromatic rings. We postulate that the edge of the aromatic rings can recognize the methyl group at the 3-position of citronellal, as the rings are oriented in a pseudoparallel orientation. We utilized the kinetic resolution for the synthesis of L-menthol from citral.

Such chiral phosphine–internal olefin hybrid type ligands as N-1-adamantyl-N-cinnamylaniline derivatives 1 with C(aryl)–N(amine) bond axial chirality were synthesized and utilized for the palladium-catalyzed asymmetric allylic alkylation of indoles to afford the desired products in high enantioselectivities (up to 98% ee).

We report a highly selective asymmetric ring-closing ene reaction catalysed by aluminum complexes with chiral BINOL. This reaction yields optically active 6-membered cyclized alcohols from unsaturated aldehydes, with good diastereo- and enantioselectivities. Asymmetric amplification of this reaction was investigated by varying the ee of the BINOL employed in the catalyst.