The diastereoselective construction of 3‐allyl‐3‐aminooxindoles that have two adjacent stereocenters has been achieved by the In‐promoted Barbier‐type addition of γ‐substituted allylic halides to the C=N bond of isatin ketimines. The reactions of cinnamyl‐, crotyl‐, and geranylindium compounds with isatin ketimines proceeded in either aqueous or alcohol solution. The addition of a cyclohexenylindium species to an isatin ketimine was carried out in N,N‐dimethylformamide (DMF), and the addition of ethyl 4‐bromocrotonate to an isatin ketimine in EtOH gave oxindole‐based β‐amino acid scaffolds. In all of these processes, the reaction conditions were screened to obtain the respective 3‐allyl‐3‐aminooxindoles with very high stereoselectivity. In addition, plausible TS models are proposed, and representative synthetic transformations were carried out by using the oxindole‐based β‐amino acid scaffolds. Furthermore, the stereochemistry of representative compounds were unequivocally established by single‐crystal X‐ray structure analysis.
A phosphite mediated stereoretentive C–H alkylation of N–alkylpyridinium salts derived from chiral primary amines was achieved. The reaction proceeds through the activation of the N–alkylpyridinium salt substrate with a nucleophilic...
Ap hosphite-mediated [2,3]-aza-Wittig rearrangement has been developed for the regio-and enantioselective allylic alkylation of six-membered heteroaromatic compounds (azaarenes). The nucleophilic phosphite adducts of N-allyl salts undergo as tereoselective base-mediated aza-Wittig rearrangement and dissociation of the chiral phosphite for overall C À Hf unctionalization of azaarenes.T his method provides efficient access to tertiary and quaternary chiral centers in isoquinoline,q uinoline,a nd pyridine systems,t olerating ab road variety of substituents on both the allyl part and azaarenes.C atalysis with chiral phosphites is also demonstrated with synthetically useful yields and enantioselectivities.
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