An unprecedented oxidative arylation reaction of terminal alkenes with simple aroyl hydrazides has been developed under aerobic conditions for the stereoselective synthesis of 1,2-disubstituted alkenes. A range of aroyl hydrazides underwent palladium/copper-catalyzed oxidative Mizoroki-Heck reaction with terminal alkenes open to air in a 1:1 mixture of dimethyl sulfoxide and acetonitrile to give structurally diverse 1,2-disubstituted alkenes in moderate to excellent yields with excellent regio- and E-selectivity. The reaction tolerated a wide variety of functional groups, such as alkoxy, hydroxy, amino, fluoro, chloro, bromo, cyano, nitro, ester, amide, imide, phosphine oxide, and sulfone groups, and, moreover, molecular oxygen and dimethyl sulfoxide were demonstrated to serve as terminal oxidants. This study provides a useful method for the stereoselective synthesis of 1,2-disubstituted alkenes through direct transformation of the vinylic CH bonds in terminal alkenes.
A new strategy has been established for the kinetic resolution of racemic allylic alcohols through a palladium/sulfonyl-hydrazide-catalyzed asymmetric OH-substitution under mild conditions. In the presence of 1 mol % [Pd(allyl)Cl]2 , 4 mol % (S)-SegPhos, and 10 mol % 2,5-dichlorobenzenesulfonyl hydrazide, a range of racemic allylic alcohols were smoothly resolved with selectivity factors of more than 400 through an asymmetric allylic alkylation of monosubstituted hydrazines under air at room temperature. Importantly, this kinetic resolution process provided various allylic alcohols and allylic hydrazine derivatives with high enantiopurity.
A tandem radical carbamoylation/cyclization reaction of N‐arylacrylamides with hydrazinecarboxamides has been developed for facile access to 2‐(oxindol‐3‐yl)acetamides, which had been utilized as precursors in the synthesis of natural bioactive pyrrolidinoindolines. In the presence of 1 mol% of copper(II) carbonate and 4 equiv. of tert‐butyl hydroperoxide, a wide range of N‐arylacrylamides underwent highly regioselective carbamoylation with hydrazinecarboxamides followed by 5‐exo‐trig cyclization to afford structurally diverse 2‐(oxindol‐3‐yl)acetamides in moderate to excellent yields.magnified image
The use of hydrazinecarboxamides as a new class of carbamoylating agents has been established through the dehydrazinative Minisci reaction of electron-deficient nitrogen heteroarenes. A wide range of electron-deficient nitrogen heteroarenes, including isoquinoline, quinoline, pyridine, phenanthridine, quinoxaline, and phthalazine, underwent copper/acid-catalyzed oxidative carbamoylation with hydrazinecarboxamide hydrochlorides to afford structurally diverse nitrogen-heteroaryl carboxamides as single regioisomers in moderate to excellent yields. The functional group tolerance was substantially demonstrated in the direct carbamoylation of quinine obviating multistep sequences involving protecting groups and prefunctionalization of the heterocycle.
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