Conformationally restricted macrocyclic analogues of combretastatins

Electrochemical formal homocoupling of sec-alcohols

Electrochemical pinacol coupling of carbonyl compounds in an undivided cell with a sacrificial anode would be a promising approach toward synthetically valuable vic-1,2-diol scaffolds without using low-valent metal reductants. However, sacrificial anodes produce an equimolar amount of metal waste, which may be a major issue in terms of sustainable chemistry. Herein, we report a sacrificial anode-free electrochemical protocol for the synthesis of pinacol-type vic-1,2-diols from sec-alcohols, namely benzyl alcohol derivatives and ethyl lactate. The corresponding vic-1,2-diols are obtained in moderate to good yields, and good to high levels of stereoselectivity are observed for sec-benzyl alcohol derivatives. The present transformations smoothly proceed in a simple undivided cell under constant current conditions without the use of external chemical oxidants/reductants, and transition-metal catalysts.

Solution-phase parallel synthesis of a multi-substituted benzo[b]thiophene library

Generation of a library using parallel syntheses of multi-substituted benzo[b]thiophenes is described. The requisite 3-iodobenzo[b]thiophenes are readily prepared in excellent yields from various alkynes bearing electron-rich aromatic rings by electrophilic cyclization using I(2) in CH(2)Cl(2). The heteroaromatic carbon-iodine bonds allow further diversification by palladium-catalyzed Suzuki-Miyaura, Sonogashira, Heck, and carboalkoxylation chemistry to give multi-substituted benzo[b]thiophene derivatives.