CAN-mediated oxidative cleavage of 4-aryl-3,4-dihydroxypiperidines

Cooperative titanocene and phosphine catalysis: accelerated C-X activation for the generation of reactive organometallics

The study presented herein describes a reductive transmetalation approach toward the generation of Grignard and organozinc reagents mediated by a titanocene catalyst. This method enables the metalation of functionalized substrates without loss of functional group compatibility. Allyl zinc reagents and allyl, vinyl, and alkyl Grignard reagents were generated in situ and used in the addition to carbonyl substrates to provide the corresponding carbinols in yields up to 99%. It was discovered that phosphine ligands effectively accelerate the reductive transmetalation event to enable the metalation of C-X bonds at temperatures as low as -40 °C. Performing the reactions in the presence of chiral diamines and amino alcohols led to the enantioselective allylation of aldehydes.

Activation of the NC–H bond of Morita–Baylis–Hillman adducts of N-substituted isatins with cerium ammonium nitrate (CAN) and alcohol (ROH)

A study on the activation of the NC–H bond of Morita–Baylis–Hillman adducts of N-substituted isatin with cerium ammonium nitrate (CAN) and saturated and unsaturated alcohols have been carried out. The choice of a Morita–Baylis–Hillman adduct for this study is screened with a number of adducts. A comparative and reactivity pattern study on NC-H activation of Morita–Baylis–Hillman adducts of N-substituted isatin derivatives viz. N-methyl, N-ethyl, N-methyl acetate, N-benzyl, N-propargyl, and N-isopropyl isatins have been carried out. Effect of aryl ring substitution has also been investigated. A plausible mechanism for the formation of the ether products has been outlined.