Enantioselective one-pot three-component synthesis of propargylamines

A copper(I) complex of i-Pr-pybox-diPh has been found to be an efficient catalyst for an enantioselective one-pot three-component synthesis of propargylamines from aldehydes, amines, and alkynes. The reaction has been applied to a wide variety of aromatic aldehydes with excellent yields (up to 99%) and enantiomeric excesses (up to 99% ee). A transition-state model has been proposed to explain the stereochemical outcome of the reaction

An efficient approach to 2-substituted N-tosylpiperdines: asymmetric synthesis of 2-(2-hydroxy substituted)piperidine alkaloids

We have developed an efficient and a general approach to chiral 2-substituted N-tosylpiperidines starting from chiral α-substituted-N-tosylaziridines. Using this approach, we have synthesized (+)-coniine. The synthesis of chiral N-tosyl-2-piperidinylethanol 15 and ent-15, was achieved from L- and D-aspartic acids, respectively in few steps. Piperidine 15 was converted into 2-(2-hydroxysubstituted)piperidines of type 2 in optically active form. By applying this strategy, asymmetric syntheses of halosaline (R,R)-2a, (+)- and (−)-sedamine 2b, (+)- and (−)-allosedamine 2c, (+)- and (−)-sedridine 2d, (+)- and (−)-allosedridine 2e, (+)-tetraponerine T-3 3a, T-4 3c, T-7 3b, and T-8 3d have been achieved in high yields. These stereoisomers can be interconverted via Mitsunobu inversion in excellent yields

An alternative to the Swern oxidation

A variety of alcohols have been oxidized under mild conditions by the DMSO–Ph3P·X2 complexes. The reaction does not produce any Pummerer product. A mechanism for the reaction is proposed

Enantioselective Friedel–Crafts alkylation of indoles with nitroalkenes catalyzed by a bis(oxazoline)–Cu(II) complex

The catalytic enantioselective Friedel–Crafts reaction of indole with trans-β-nitrostyrene is reported in the presence of copper triflate–bisoxazoline complexes. The reaction furnished nitroalkylated indoles in excellent yields (up to 95%) and high enantioselectivities up to an 86% ee

Enantioselective diethylzinc addition to aldehydes catalyzed by Ti(IV) complex of unsymmetrical chiral bis(sulfonamide) ligands of trans-cyclohexane 1,2-diamine

Titanium(IV) complexes of bidentate trans-cyclohexane 1,2-diamine-based unsymmetrical chiral bis(sulfonamide) ligands were evaluated as catalysts for the asymmetric addition of diethylzinc to aldehydes. The reaction provided secondary alcohols in quantitative yields and very good enantioselectivity (up to 96% ee)

Enantioselective turnover in glyoxylate-ene reactions catalyzed by chiral copper complexes

The catalytic, enantioselective carbonyl-ene reaction of ethyl glyoxylate with α-methylstyrene and 4-halo-α-methylstyrene has been investigated in the presence of copper triflate–bisoxazoline complexes. The reaction proceeded smoothly to give γ,δ-unsaturated-α-hydroxy esters in moderate to good yields and with excellent enantioselectivity (up to 100% ee). A hypothesis has been provided to explain the reversal of enantioselectivity in the reaction

Activation of DMSO by phosphonitrilic chloride: an efficient method for oxidation of alcohols

A variety of alcohols have been oxidized under mild conditions by a dimethylsulfoxide (DMSO)–chlorophosphazene complex. Sensitive groups such as silyl and tetrahydropyranyl (THP) ethers are stable under this condition

Regioselective ring opening of aziridines with activated DMF complexes: a facile synthesis of β-haloamines

A wide variety of aziridines were converted to the corresponding β-haloamines using activated DMF complexes in good to excellent yields with high regioselectivity

Trimethylsilyl cyanide addition to aldimines and its application in the synthesis of (S)-phenylglycine methyl ester

The addition of TMSCN to a variety of arylaldimines (Strecker reaction) in the presence of LiClO4 or BF3·Et2O in acetonitrile has been studied. The reaction provided the addition products in very high yields. The method has been successfully utilized for the synthesis of (S)-phenylglycine methyl ester

Synthesis of chiral vicinal C<SUB>2</SUB> symmetric and unsymmetric bis(sulfonamide) ligands based on trans-1,2-cyclohexanediamine by aminolysis of N-tosylaziridines

The ring opening of N-tosylaziridines with aliphatic amines can be efficiently catalyzed by lithium perchlorate to provide derivatives of the trans-1,2-diamine in high yields. The reaction was used in desymmetrization of several cyclic N-tosylaziridines using chiral amines. Using this strategy, an efficient synthesis of chiral vicinal C<SUB>2</SUB> symmetric bis(sulfonamide) and unsymmetrical bis(sulfonamide) ligands based on trans-1,2-cyclohexanediamine was developed