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A convenient two step procedure to access highly functionalized chiral allenes using chiral N -methylcamphanyl piperazine derivatives is described. In this transformation, chiral propargylamines are obtained in 79–96% yields with up to 99:1 dr by the CuBr catalyzed reactions of chiral piperazine derivatives with 1-alkynes and aldehydes containing functional groups, which are converted into chiral allenes in the presence of zinc bromide, affording the chiral allenes in 59–85% yields and with up to 99% ee. The antifungal agent Sapium japonicum and an allene precursor intermediate for the synthesis of the pheromone of the male dried bean beetle 15 are obtained in 72–78% yields and with up to 98% ee following this methodology.

The reaction of unsubstitued camphanyl-piperazine 4 with ZnCl2, phenylacetylene, and benzaldehyde in toluene gave the corresponding dipropargylamine (i.e., 15) with opposite configurations at the newly formed stereogenic centres, which, upon reaction with ZnI2 resulted in the formation of a racemic mixture of 1,3-diphenyl allene in 45 % yield. N-Methylcamphanyl-piperazine regioisomer 5, prepared by selective N-methylation of the NH moiety attached to the stereogenic centre with (S)-configuration, upon reaction with ZnCl2, phenylacetylene, and benzaldehyde in toluene, gave the corresponding propargylamine in 90 % yield, with an (S)-configuration at the newly formed stereogenic centre, and upon subsequent reaction with ZnI2, this intermediate gave (R)-1,3-diphenyl allene in 52 % yield and with 96 % ee. Reaction of N-methylcamphanyl-piperazine isomer 5 with several 1-alkynes and aldehydes in the presence of ZnBr2 gave the corresponding (R)-allenes in 40–75 % yield and 79–99 % ee. In contrast, regioisomeric N-methylcamphanyl-piperazine 6 reacted with ZnBr2 to give the corresponding (S)-allenes in 38–71 % yield and with 79–99 % ee. The opposite chiral discriminating abilities of the two NH moieties in camphanyl-piperazines was confirmed by single-crystal X-ray analysis of the propargylamines formed. The results are discussed considering mechanisms involving the in situ formation of alkynylzinc halides, followed by diastereoselective addition to chiral iminium ion derivatives to give the corresponding propargylamines, and subsequent conversion to chiral allenes by an intramolecular 1,5-hydrogen shift.

Chiral allenes are readily accessed in a single pot operation in the reaction of terminal alkynes, aldehydes, chiral secondary amines, and zinc halides in good yields (up to 77% yield) and excellent enantioselectivities (up to 99% ee) in toluene at 120 °C. The reaction proceeds through initial formation of chiral propargylamine intermediates with creation of a new stereogenic center and subsequent chirality transfer via an intramolecular hydride shift to produce chiral allenes with high enantiomeric purities.

A new chiral C 2 -symmetric N , N ′-bis(isobornyl)ethylenediamine–copper complex is found to be an efficient catalyst in the enantioselective Henry reaction between nitromethane and various aldehydes to provide β-hydroxy nitroalkanes with high chemical yield (up to 95%) and high enantiomeric excess (up to 90%).

Diborane is readily generated in situ at 25 °C in toluene using the Bu 4 NBH 4 /PhCH 2 Cl and Bu 4 NBH 4 /I 2 reagent systems. The reagent prepared in this way is used for the reduction of carbonyl compounds and hydroboration–oxidation of olefins to obtain the corresponding alcohols in good yields.

A convenient two step procedure to access highly functionalized chiral allenes using chiral N -methylcamphanyl piperazine derivatives is described. In this transformation, chiral propargylamines are obtained in 79–96% yields with up to 99:1 dr by the CuBr catalyzed reactions of chiral piperazine derivatives with 1-alkynes and aldehydes containing functional groups, which are converted into chiral allenes in the presence of zinc bromide, affording the chiral allenes in 59–85% yields and with up to 99% ee. The antifungal agent Sapium japonicum and an allene precursor intermediate for the synthesis of the pheromone of the male dried bean beetle 15 are obtained in 72–78% yields and with up to 98% ee following this methodology.

A versatile and efficient synthesis of axial chiral allenes with high enantiopurities is developed.

Simple, convenient methods have been developed using readily available, easy-to-handle reagents to access a variety of chiral amino alcohols and amines, which have considerable potential for applications in asymmetric organic transformations. Scholars from this laboratory in India have made significant contributions to this field, which is the subject of the current review.

Chiral allenes are readily accessed in a single pot operation in the reaction of terminal alkynes, aldehydes, chiral secondary amines, and zinc halides in good yields (up to 77% yield) and excellent enantioselectivities (up to 99% ee) in toluene at 120 °C. The reaction proceeds through initial formation of chiral propargylamine intermediates with creation of a new stereogenic center and subsequent chirality transfer via an intramolecular hydride shift to produce chiral allenes with high enantiomeric purities.

A new chiral C 2 -symmetric N , N ′-bis(isobornyl)ethylenediamine–copper complex is found to be an efficient catalyst in the enantioselective Henry reaction between nitromethane and various aldehydes to provide β-hydroxy nitroalkanes with high chemical yield (up to 95%) and high enantiomeric excess (up to 90%).

Diborane is readily generated in situ at 25 °C in toluene using the Bu 4 NBH 4 /PhCH 2 Cl and Bu 4 NBH 4 /I 2 reagent systems. The reagent prepared in this way is used for the reduction of carbonyl compounds and hydroboration–oxidation of olefins to obtain the corresponding alcohols in good yields.