01444nas a2200205 4500008004100000022001400041245003200055210003200087260000800119300001400127490000700141520092000148100001701068700002001085700001501105700001901120700001701139700001901156856006301175 2023 eng d a2041-652000aTaming the parent oxoborane0 aTaming the parent oxoborane cJUN a5894-58980 v143 a

Despite recent advancements in the chemistry of multiply bound boron compounds, the laboratory isolation of the parent oxoborane moiety, HBO has long remained an unsolved and well-recognized challenge. The reaction of 6-SIDipp(.)BH3 [6-SIDipp = 1,3-di(2,6-diisopropylphenyl)tetrahydropyrimidine2-ylidene] with GaCl3 afforded an unusual boron-gallium 3c-2e compound (1). The addition of water to 1 resulted in the release of H-2 and the formation of a rare acid stabilized neutral parent oxoborane, LB(H)]O (2). Crystallographic and density functional theory (DFT) analyses support the presence of a terminal B=O double bond. Subsequent addition of another equivalent of water molecule led to hydrolysis of the B-H bond to the B-OH bond, but the `B=O' moiety remained intact, resulting in the formation of the hydroxy oxoborane compound (3), which can be classified as a monomeric form of metaboric acid.

1 aKundu, Gargi1 aAmrutha, P., R.1 aRaj, Vipin1 aTothadi, Srinu1 aVanka, Kumar1 aSen, Sakya, S. uhttps://library.ncl.res.in/content/taming-parent-oxoborane02304nas a2200229 4500008004100000022001400041245011900055210006900174260000900243490000700252520151600259653001001775653002401785653002701809653001901836653001301855100001701868700002001885700001901905700001901924856013101943 2024 eng d a0947-653900aAccess to NHC-Boryl mono- and bis-selenide and utility as mild selenium transfer reagent including to the C-F bond0 aAccess to NHCBoryl mono and bisselenide and utility as mild sele cJAN 0 v303 a

Reactions of 5-SIDipp & sdot; BH3 (5-SIDipp=1,3-bis(2,6-diisopropylphenyl)-imidazolin-2-ylidene) (1) with diphenyldiselenide provide access to 5-SIDipp-boryl mono- (5-SIDipp & sdot; BH2SePh) (2) and bis-selenide (5-SIDipp & sdot; BH(SePh)2) (3). The facile cleavage of the B-Se bond makes 2 a neutral source of selenium nucleophiles in substitutions reactions with benzyl bromides, and provide access to the corresponding selenoethers. The direct transformations of one of the C(sp2)-F bonds of C5F5N and C6F5CF3 to C-Se bonds have also been achieved by the use of 2 without employing transition-metal catalysts. While it was previously established that C6F6 could undergo complete defluoroselenation under harsh conditions, we successfully achieved partial defluorination of C6F6 by employing 2 as a mild selenide transfer reagent. During the formation of C-Se bonds through the cleavage of C-F bonds, the potential by-product NHC & sdot; BH2F undergoes ring expansion of the NHC, leading to the formation of the six-membered diaazafluoroborinane (7). Access to NHC & sdot; boryl mono- and bis-selenides from NHC & sdot; BH3 has been achieved. The boryl mono selenide has been demonstrated to function as a selenium transfer reagent, enabling the synthesis of selenoethers from benzyl bromide. Additionally, it can also facilitate the conversion of the challenging aromatic C-F bond to a C-Se bond, resulting in concomitant ring expansion of NHC & sdot; haloborane.image

10aboron10aC-F Bond Activation10aN-Heterocyclic carbene10aRing expansion10aSelenium1 aKundu, Gargi1 aAmrutha, P., R.1 aTothadi, Srinu1 aSen, Sakya, S. uhttps://library.ncl.res.in/content/access-nhc-boryl-mono-and-bis-selenide-and-utility-mild-selenium-transfer-reagent-including00708nas a2200205 4500008004100000022001400041245010500055210006900160260000900229300001400238490000700252653001500259653001300274653001400287100001700301700002000318700001900338700001900357856012600376 2024 eng d a0276-733300aSaturated NHC-stabilized borenium, boronium, hydride-bridged boron cations, and a bora-acyl chloride0 aSaturated NHCstabilized borenium boronium hydridebridged boron c cJUN  a1355-13610 v4310aactivation10aBORINIUM10aChemistry1 aKundu, Gargi1 aAmrutha, P., R.1 aTothadi, Srinu1 aSen, Sakya, S. uhttps://library.ncl.res.in/content/saturated-nhc-stabilized-borenium-boronium-hydride-bridged-boron-cations-and-bora-acyl02014nas a2200205 4500008004100000022001400041245016000055210006900215260000800284300001400292490000700306520122100313100002001534700001701554700002801571700002401599700003201623700001901655856013401674 2026 eng d a1477-922600aReactions of saturated NHC·boranes with electron-deficient alkynes and alkenes. borirane formation, their reactivities, and coupling of tetracyanoethylene0 aReactions of saturated NHC boranes with electrondeficient alkyne cJUN a8356-83650 v553 a

In this study, we describe the reactions of five- and six-membered saturated N-heterocyclic carbene boranes (NHC & centerdot;BH3) with electron-deficient alkenes and alkynes. Notably, both five- and six-membered saturated NHCs form boriranes upon the reaction of NHC & centerdot;BH3 with dimethyl acetylene dicarboxylate (DMAD). However, their reactivity with HCl differs: the five-membered saturated NHC-stabilized borirane undergoes ring opening in toluene/THF, whereas the six-membered saturated NHC-stabilized borirane undergoes ring expansion, forming exclusively a boralactone irrespective of solvent. Interestingly, when acetonitrile is used as a solvent, the five-membered saturated NHC-stabilized borirane yields both ring-opening and ring-expansion products. To remove the hydrogen attached to the boron atom in boriranes, we reacted the five-membered saturated NHC-stabilized borirane with AlCl3 and B(C6F5)(3), resulting in azaborolium cation or adduct formation, respectively. Transitioning from an electron-deficient alkyne to an alkene, the reaction of six-membered saturated NHC & centerdot;BH3 with tetracyanoethylene (TCNE) led to the unusual coupling of two TCNE molecules.

1 aAmrutha, P., R.1 aKundu, Gargi1 aGanesh, Vemuri, Lakshmi1 aGonnade, Rajesh, G.1 aGopakumar, Gopinadhanpillai1 aSen, Sakya, S. uhttps://library.ncl.res.in/content/reactions-saturated-nhc%C2%B7boranes-electron-deficient-alkynes-and-alkenes-borirane-formation