@article {46251, title = { Phosphite-Catalyzed C-H allylation of azaarenes via an enantioselective [2,3]-Aza-wittig rearrangement }, journal = {Angewandte Chemie-International Edition}, year = {2019}, month = {AUG}, type = {Article}, abstract = {

A phosphite-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 a stereoselective base-mediated aza-Wittig rearrangement and dissociation of the chiral phosphite for overall C-H functionalization of azaarenes. This method provides efficient access to tertiary and quaternary chiral centers in isoquinoline, quinoline, and pyridine systems, tolerating a broad variety of substituents on both the allyl part and azaarenes. Catalysis with chiral phosphites is also demonstrated with synthetically useful yields and enantioselectivities.

}, doi = {10.1002/anie.201906681}, author = {Motaleb, Abdul and Rani, Soniya and Das, Tamal and Gonnade, Rajesh G. and Maity, Pradip} } @article {47594, title = {Phosphite mediated asymmetric N to C migration for the synthesis of chiral heterocycles from primary amines}, journal = {Chemical Science}, volume = {12}, year = {2021}, month = {JUL}, pages = {8996-9003}, type = {Article}, abstract = {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 phosphite catalyst, followed by a base mediated [1,2] aza-Wittig rearrangement and subsequent catalyst dissociation for an overall N to C-2 alkyl migration. The scope and degree of stereoretention were studied, and both experimental and theoretical investigations were performed to support an unprecedented aza-Wittig rearrangement-rearomatization sequence. A catalytic enantioselective version starting with racemic starting material and chiral phosphite catalyst was also established following our understanding of the stereoretentive process. This method provides efficient access to tertiary and quaternary stereogenic centers in pyridine systems, which are prevalent in drugs, bioactive natural products, chiral ligands, and catalysts.}, issn = {2041-6520}, doi = {10.1039/d1sc01217g}, author = {Rani, Soniya and Dash, Soumya Ranjan and Bera, Asish and Alam, Md Nirshad and Vanka, Kumar and Maity, Pradip} } @article {48260, title = {Organophosphites: an addition to the arsenal of organocatalysts}, journal = {European Journal of Organic Chemistry}, volume = {26}, year = {2023}, month = {JAN}, type = {Review}, abstract = {

Organophosphites are nucleophilic in nature and can act as a good leaving group owing to the stability of the phosphite anion. This dual reactivity makes them good candidates for nucleophilic organocatalysis. However, phosphites were introduced only in 2004 as the umpolung catalyst for acylsilane substrates utilizing sequential Brook rearrangements. Very recently, phosphites have been reported to catalyze aza-rearrangements and radical reactions. In this review, we discuss the reactivity parameters to understand its lack of use, as well as the potential for catalysis.

}, keywords = {acylradical, azaacyl equivalent, cylanion, organocatalysis, phosphite}, issn = {1434-193X}, doi = {10.1002/ejoc.202201238}, author = {Baral, Nilofar and Rani, Soniya and Saikia, Pinku and Maity, Pradip} }