@article {42738, title = {Unified strategy for nickel-catalyzed C-2 Alkylation of indoles through chelation assistance}, journal = {ACS Catalysis}, volume = {6}, year = {2016}, month = {JUL}, pages = {5666{\textendash}5672}, abstract = {

A nickel-catalyzed direct C-2 alkylation of indoles through monodentate-chelation assistance has been described. This reaction proceeds via an unusual strategy by the use of a well-designed and defined (quinolinyl)amido{\textendash}nickel catalyst, [{κN,κN,κN-Et2NCH2C(O)(μ-N)C9H6N}Ni(OAc)], providing a solution to the limitations associated with bidentate-chelate auxiliaries. The method allows coupling of indoles with various unactivated primary and secondary alkyl halides with ample substrate scope. This uniquely strategized alkylation proceeded through crucial C{\textendash}H activation and via an alkyl radical intermediate. The reaction by this approach represents a rare example of Ni-catalyzed monodentate-chelate-assisted C{\textendash}H functionalization.

}, doi = {10.1021/acscatal.6b02003}, author = {Soni, Vineeta and Jagtap, Rahul A. and Gonnade, Rajesh G. and Punji, Benudhar} } @article {45733, title = {Unified approach to fused and spirocyclic oxindoles through lewis-acid-promoted opening of spiroepoxyoxindoles with allylsilanes: application to the formal synthesis of (+/-)-physovenine}, journal = {European Journal of Organic Chemistry}, year = {2017}, month = {MAY }, pages = {2603-2609}, type = {Article}, abstract = {

A protocol for the construction of oxindoles containing all-carbon quaternary centres in a highly regioselective manner has been developed. The reaction involves opening of spiroepoxyoxindoles with allylsilanes to give Hosomi-Sakurai-type products as well as new silicon-containing spirocyclic oxindoles. A formal synthesis of (+/-)-physovenine was accomplished in five steps using this protocol.

}, keywords = {alkaloids, Allylation, annulation, Lewis acids, spiro compounds}, issn = {1434-193X}, doi = {10.1002/ejoc.201700259}, author = {Sharma, Brijesh M. and Yadav, Mahesh and Gonnade, Rajesh G. and Kumar, Pradeep} } @article {43866, title = {Unprecedented solvent induced inter-conversion between monomeric and dimeric silylene-zinc iodide adducts}, journal = {Dalton Transaction }, volume = {46}, year = {2017}, month = {SEP}, chapter = {11418-11424}, abstract = {

Usually, when a silylene reacts with a transition metal Lewis acid, it forms an adduct which could be either monomeric or dimeric. However, we present here that a silylene, [PhC(NtBu)(2)SiN(SiMe3)(2)] can form both monomeric [PhC(NtBu)(2)Si{N(SiMe3)(2)} -\> ZnI2]center dot THF (1) and dimeric [{PhC(NtBu)(2)}(N(SiMe3)(2))SiZnI,(mu-I)](2) (2) adducts upon reaction with ZnI2. The formation of 1 and 2 relies upon the solvent used for the reaction or crystallization. When the crystallization is carried out in THF complex 1 is formed, however, when the reaction and crystallization are performed in acetonitrile complex 2 is obtained. Both 1 and 2 were structurally authenticated and the nature of the Si-Zn bond in these complexes was determined by quantum chemical calculations. In addition, a spontaneous inter-conversion between 1 and 2 just by changing the solvents has been also observed; a feature presently not known for silylene-transition metal Lewis adducts.

}, keywords = {Bis(Silylene ), Carbene Complexes, Crystal -structure Determination, Dative bond, Lewis acid base reaction, Ligands, Main- group compounds, Reactivity, Silicon(II) Bis(Trimethylsilyl)Amide; Carbonyl-Complexes}, issn = {1477-9226}, doi = {10.1039/c7dt01823a}, author = {Yadav, Sandeep and Sangtani, Ekta and Dhawan, Diksha and Gonnade, Rajesh G. and Ghosh, Debashree and Sen, Sakya S.} } @article {44384, title = {Unravelling the nucleophilicity of buten tides for 1,6-conjugate addition to p-quinone methides: a direct access to diversely substituted butenolide-derived diarylmethanes}, journal = {Organic Letters}, volume = {20}, year = {2018}, month = {MAY}, pages = {2787-2791}, abstract = {A Lewis acid catalyzed regioselective C-C bond is constructed through beta-addition of deconjugated butenolides with p-quinone methides in a 1,6-conjugate addition manner. Interestingly, Lewis acid catalyzed vinylogous Mukaiyama-Michael reaction of silyloxyfurans with p-QMs proceeds selectively through the alpha or gamma position exclusively. The reaction is mild with broad substrate scope, thus allowing easy access to a wide range of bis-arylated alpha-/beta-/gamma-substituted butenolides.}, doi = {10.1021/acs.orglett.8b00745}, author = {Sharma, Brijesh M. and Shinde, Dinesh R. and Jain, Ruchi and Begari, Eeshwaraiah and Satbhaiya, Shruti and Gonnade, Rajesh G. and Kumar, Pradeep} } @article {47654, title = {Unsymmetrical sp(2)-sp(3) disilenes}, journal = {Angewandte Chemie-International Edition}, volume = {60}, year = {2021}, month = {SEP }, pages = {20706-20710}, type = {Article}, abstract = {Disilenes with differently coordinated silicon atoms are not known. Here, we have shown the high yield synthesis of a range of disilenes (2-4 and 6) upon reaction of a hypersilyl silylene PhC(NtBu)(2)SiSi(SiMe3)(3) (1) with aliphatic chlorophosphines. The most striking characteristic of these disilenes is the presence of two differently coordinated Si atoms (one is three-coordinated, the other four-coordinated). The analogous reaction with Ph2PCl did not afford the desired disilene, but, surprisingly, led to the first tetraphosphinosilane (8). DFT calculations were performed to understand the bonding in disilenes and differences in reactivity of the complexes.}, keywords = {chlorophosphine, DFT, disilene, hypersilylsilylene}, issn = {1433-7851}, doi = {10.1002/anie.202107847}, author = {Bisai, Milan Kumar and Das, Tamal and Vanka, Kumar and Gonnade, Rajesh G. and Sen, Sakya S.} }