@article { ISI:000361190200026, title = {Intramolecular cyclization of carbonate and thiocarbonate derivatives of myo-inositol in the solid state: implications for acyl group transfer reactions in molecular crystals}, journal = {Chemistry-A European Journal}, volume = {21}, number = {39}, year = {2015}, month = {SEP}, pages = {13676-13682}, publisher = {WILEY-V C H VERLAG GMBH}, address = {POSTFACH 101161, 69451 WEINHEIM, GERMANY}, abstract = {

Racemic 4-O-phenoxycarbonyl and 4-O-phenoxythiocarbonyl derivatives of myo-inositol orthoformate undergo thermal intramolecular cyclization in the solid state to yield the corresponding 4,6-bridged carbonates and thiocarbonates, respectively. The thermal cyclization also occurs in the solution and molten states, but less efficiently, suggesting that these cyclization reactions are aided by molecular pre-organization, although not strictly topochemically controlled. Crystal structures of two carbonates and a thiocarbonate clearly revealed that the relative orientation of the electrophile and the nucleophile in the crystal lattice facilitates the intramolecular cyclization reaction and forbids the intermolecular reaction. The correlation observed between the chemical reactivity and the non-covalent interactions in the crystal of the reactants provides a way to estimate the chemical stability of analogous molecules in the solid state.

}, keywords = {crystal engineering, cyclitols, inositols, nucleophilic substitution, solid-phase synthesis}, issn = {0947-6539}, doi = {10.1002/chem.201501480}, author = {Tamboli, Majid I. and Shashidhar, Mysore S. and Gonnade, Rajesh G. and Krishnaswamy, Shobhana} } @article {45600, title = {Unusual route to synthesize indolizines through a domino SN2/michael addition reaction between 2-mercaptopyridine and nitroallylic acetates}, journal = {European Journal of Organic Chemistry}, year = {2019}, month = {JAN}, pages = {765-769}, type = {Article}, abstract = {

A straightforward synthesis of indolizines has been demonstrated from the reaction of 2-mercaptopyridine and nitroallylic acetates in the presence of a base. The products were obtained in good isolated yield under relatively mild reaction conditions. The mechanistic insight of the reaction has been revealed by performing some control experiments demonstrating that the reaction is initiated by a sequential SN2/Michael addition reaction followed by removal of the sulfur moiety.

}, keywords = {domino reactions, Michael addition, nitrogen heterocycles, nucleophilic substitution, synthetic methods}, issn = {1434-193X}, doi = {10.1002/ejoc.201801426}, author = {Roy, S.} } @article {48142, title = {Nucleophilic substitution at a coordinatively saturated five-membered NHC center dot haloborane centre}, journal = {Inorganics}, volume = {10}, year = {2022}, month = {JUL}, pages = {97}, type = {Article}, abstract = {

In this paper, we have used a saturated five-membered N-Heterocyclic carbene (5SIDipp = 1,3-bis-(2,6-diisopropylphenyl)imidazolin-2-ylidine) for the synthesis of SNHC-haloboranes adducts and their further nucleophilic substitutions to put unusual functional groups at the central boron atom. The reaction of 5-SIDipp with RBCl2 yields Lewis-base adducts, 5-SIDipp center dot RBCl2 [R = H (1), Ph (2)]. The hydrolysis of 1 gives the NHC stabilized boric acid, 5-SIDipp center dot B(OH)(3) (3), selectively. Replacement of chlorine atoms from 1 and 2 with one equivalent of AgOTf led to the formation of 5-SIDipp center dot HBCl(OTf) (4) and 5-SIDipp center dot PhBCl(OTf) (5a), where all the substituents on the boron atoms are different. The addition of two equivalents of AgNO3 to 2 leads to the formation of rare di-nitro substituted 5-SIDipp center dot BPh(NO3)(2) (6). Further, the reaction of 5-SIDipp with B(C6F5)(3) in tetrahydrofuran and diethyl ether shows a frustrated Lewis pair type small molecule activated products, 7 and 8.

}, keywords = {NHC-haloboranes, nucleophilic substitution, saturated NHC, tetra-coordinate boron}, doi = {10.3390/inorganics10070097}, author = {Kundu, Gargi and Tothadi, Srinu and Sen, Sakya S.} }