A general Ni-catalyzed process for the cross-coupling of secondary alkylzinc halides and aryl/heteroaryl iodides has been developed. This is the first process to overcome the isomerization and β-hydride elimination problems that are associated with the use of secondary nucleophiles, and that have limited the analogous Pd-catalyzed systems. The impact of salt additives was also investigated. It was found that the presence of LiBF(4) dramatically improves both isomeric retention and yield for challenging substrates.
Highly enantio- and diastereoselective organocatalytic Mannich additions of alpha-isothiocyanato imides to sulfonyl imines are reported. Enantiomerically enriched syn-alpha,beta-diamino acid derivatives can be obtained in excellent yields using catalyst loadings as low as 0.25 mol %.
Recent advances in the chemistry of base-, metal-, nano-metal and organo-catalyst mediated achiral and chiral versions of the structurally diverse and pharmaceutically relevant spirooxindoles are gently reviewed.
A molecular electron density theory (MEDT) study for the [3 + 2] cycloaddition (32CA) reaction of indoledione and N-methyl glycine with (E)-1-bromonitrostyrene leading to the spirooxindole-pyrrolidine adduct is presented. Electron localisation function (ELF) study of the in situ generated azomethine ylide classifies a pseudodiradical electronic structure associated with low activation energies. This 32CA reaction is a polar process with electronic flux from the strongly nucleophilic azomethine ylide to the strongly electrophilic nitrostyrene, confirmed from the global electron density transfer (GEDT) above 0.20 e at the transition states (TSs). Parr function analysis predicts the correct regioselectivity from the two-centre interactions. The reaction is kinetically controlled with negative free energy of reaction which makes it irreversible. The activation enthalpy of the favoured TS is lowered by 3.4, 6.3 and 9.3 kcal mol −1 in methanol relative to the other feasible reaction paths,
Diastereoselective [3 + 2]-cycloadditions of oxindoles with α,β-disubstituted nitroethylenes: regioreversed spiropyrrolidines show potent MRSA activity.
β-Nitrostyrenes undergo one pot sequential addition-elimination reaction when reacted with finely powdered iodine in presence of sodium bicarbonate as base in water and tetrahydrofuran as solvents to afford seventeen α-iodonitroalkenes in moderate to good yields (40-88 %). These compounds were tested for activity against Mycobacterium tuberculosis H37Ra and MIC was determined using Rifampicin as positive control. One of the iodo compound 14 b, exhibited promising antimycobacterial activity with MIC values of up to 3.125 μM. Further, twelve α-Iodonitroalkenes exhibited significant antifungal activity against Candida albicans, Cryptococcus neoformans and drug-reistant Candida auris. with MIC values up to � 0.25 μM. This opens up the new space in the development of novel pharmacophores for antifungal and antimycobacterial studies.
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