A highly regioselective Lewis acid-mediated S(N)2-type ring-opening of N-sulfonylaziridines and azetidines with tetraalkylammonium halides in CH(2)Cl(2) solution to afford 1,2- and 1,3-haloamines in excellent yields is described. An easy diastereoselective route toward substituted chiral N-tosylaziridines has been developed. The mechanism of ring-opening via S(N)2 pathway has been confirmed by the formation of chiral haloamines with excellent er and dr. Chloroamines obtained from 2,3-disubstituted aziridines were converted to the chiral N-tosylamines via radical dehalogenation.
A highly enantio- and diastereoselective Lewis acid catalyzed S(N)2-type ring opening followed by cyclization of aziridines with active methylene carbon nucleophiles to functionalized chiral γ-lactams in a domino fashion has been developed. γ-Lactams have been desulfonated and decarboxylated, providing pyrrolidone-3-carboxylate and N-tosylpyrrolidinone derivatives, respectively, in good yields.
4-Unsubstituted 1,2-benzothiazines are prepared from sulfoximines and allyl methyl carbonate by Rh(III)-catalyzed domino allylation/oxidative cyclization. A wide range of functional groups on the sulfoximine are tolerated. A plausible mechanism is proposed, and chemical modifications of the products have been explored.
A new domino synthetic approach for the synthesis of highly functionalized tetrahydrocarbazoles via DROC of various functionalized DA-cyclopropanes with 2-indolylnitroethylene and indole-substituted alkylidene malonate is described. The tetrahydrocarbazoles were obtained with excellent diastereoselectivity having cis alignment of the 1,4-appendages across the six-membered carbocyclic ring.
An atom transfer radical addition elimination (ATRE) reaction of terminal alkenes with perfluoroalkyl halides under visible light is described. The photoredox catalysis with Eosin Y provides perfluoroalkenes in good yields. The reaction has been utilized for the late stage perfluoroalkenylation of an estrone-derived alkene.
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