02105nas a2200157 4500008004100000245010900041210006900150260000800219520149800227100001901725700001701744700001501761700002401776700001801800856012901818 2019 eng d00a Phosphite-Catalyzed C-H allylation of azaarenes via an enantioselective [2,3]-Aza-wittig rearrangement 0 aPhosphiteCatalyzed CH allylation of azaarenes via an enantiosele cAUG3 a

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.

1 aMotaleb, Abdul1 aRani, Soniya1 aDas, Tamal1 aGonnade, Rajesh, G.1 aMaity, Pradip uhttps://library.ncl.res.in/content/phosphite-catalyzed-c-h-allylation-azaarenes-enantioselective-23-aza-wittig-rearrangement01692nas a2200205 4500008004100000022001400041245011200055210006900167260000800236300001400244490000700258520097800265100001701243700002501260700001601285700002201301700001701323700001801340856012801358 2021 eng d a2041-652000aPhosphite mediated asymmetric N to C migration for the synthesis of chiral heterocycles from primary amines0 aPhosphite mediated asymmetric N to C migration for the synthesis cJUL a8996-90030 v123 aA 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.1 aRani, Soniya1 aDash, Soumya, Ranjan1 aBera, Asish1 aAlam, Md, Nirshad1 aVanka, Kumar1 aMaity, Pradip uhttps://library.ncl.res.in/content/phosphite-mediated-asymmetric-n-c-migration-synthesis-chiral-heterocycles-primary-amines01273nas a2200229 4500008004100000022001400041245006800055210006700123260000800190490000700198520059100205653001600796653002300812653001300835653002000848653001400868100001900882700001700901700001800918700001800936856008900954 2023 eng d a1434-193X00aOrganophosphites: an addition to the arsenal of organocatalysts0 aOrganophosphites an addition to the arsenal of organocatalysts cJAN0 v263 a

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.

10aacylradical10aazaacyl equivalent10acylanion10aorganocatalysis10aphosphite1 aBaral, Nilofar1 aRani, Soniya1 aSaikia, Pinku1 aMaity, Pradip uhttps://library.ncl.res.in/content/organophosphites-addition-arsenal-organocatalysts02241nas a2200217 4500008004100000022001400041245015800055210006900213260000800282300001400290490000700304520143800311100001701749700002101766700003001787700002801817700001701845700001601862700001801878856012701896 2025 eng d a2041-652000aPhosphite mediated molecular editing via switch to meta-C-H alkylation of isoquinolines: emergence of a distinct photochemical [1,3] N to C rearrangement0 aPhosphite mediated molecular editing via switch to metaCH alkyla cJAN a1809-18180 v163 a

The isoquinoline core is present in one of the largest subsets of bioactive natural products. The multifunctional isoquinoline core exerts diverse bioactivity, resulting in the development of numerous isoquinoline-based drugs and molecules that are currently under clinical trials. We developed a new approach for phosphite-mediated [1,2] alkyl migration for an overall ortho-C-H alkylation via N-alkylation of isoquinoline. Tuning the phosphite-mediated protocol to switch the site selectivity would expedite direct and diverse multi-C-H bond functionalization. We report a new approach starting with a simple N-alkylation of isoquinoline with sterically and electronically diverse alkyl bromides for their phosphite-mediated photochemical [1,3] N to C rearrangement followed by a rearomatization sequence that leads to meta-C-H (C4) alkylation. Combined experimental and computational studies unveiled the emergence of an unprecedented C-N bond cleavage pathway from the singlet excited state of the enamine-type intermediate. Our radical bond-cleavage pathway favors substituted alkyl group migration that complements the recently successful meta-alkylation methods with smaller and more reactive electrophiles. This switch in site selectivity via tuning the phosphite-mediated protocol resulted in sequential C-H difunctionalization of isoquinoline including regiodivergent ortho, meta-dialkylations of isoquinolines.

1 aRani, Soniya1 aRay, Anuj, Kumar1 aDewangan, Devendra, Kumar1 aPatil, Nita, Aruna Ramc1 aAarthika, M.1 aPaul, Ankan1 aMaity, Pradip uhttps://library.ncl.res.in/content/phosphite-mediated-molecular-editing-switch-meta-c-h-alkylation-isoquinolines-emergence