It has been shown for the first time that relatively electron deficient triazolium pre-catalysts ... more It has been shown for the first time that relatively electron deficient triazolium pre-catalysts promote (at low loadings in the presence of base) highly chemoselective crossed acyloin condensation reactions between aldehydes and α-ketoesters to afford densely functionalized products incorporating a quaternary stereocentre of considerable synthetic potential. Hydroacylation pathways which have hitherto been dominant in these reactions can be completely avoided. The scope of the process is extraordinarily broad with respect to both coupling partners, and a preliminary study has established the principle that a high degree of stereochemical control over the reaction can also be exercised via the use of a chiral NHC precursor. It has also been shown for the first time that coupling of benzyl α-ketoesters with aldehydes followed by acylation and simple hydrogenolysis furnishes a product formally derived from the chemoselective 1 : 1 coupling of two different aliphatic aldehydes in high ...
ABSTRACT Triazolium salt TRB in combination with K2CO3 is an efficient catalyst for the coupling ... more ABSTRACT Triazolium salt TRB in combination with K2CO3 is an efficient catalyst for the coupling reaction of aliphatic or aromatic/heteroaromatic aldehydes with α-ketoesters.
ABSTRACT Sequential oxidative cleavage of cyclic 1,2-diones with water as the nucleophile and est... more ABSTRACT Sequential oxidative cleavage of cyclic 1,2-diones with water as the nucleophile and esterification of the resulting diol allows the synthesis of various diesters.
It has been shown for the first time that relatively electron deficient triazolium pre-catalysts ... more It has been shown for the first time that relatively electron deficient triazolium pre-catalysts promote (at low loadings in the presence of base) highly chemoselective crossed acyloin condensation reactions between aldehydes and α-ketoesters to afford densely ...
ABSTRACT The first organocatalytic aerobic oxidative cleavage of cyclic 1,2-diketones is reported... more ABSTRACT The first organocatalytic aerobic oxidative cleavage of cyclic 1,2-diketones is reported. The reaction occurs in either aqueous or alcoholic media and is promoted by a simple N-heterocyclic carbene catalyst derived from a 1,2,4-triazolium ion. No strong oxidants are required. The application of the process in a one-pot synthesis of a cyclic anhydride is also possible.
Benzoin (and neither the Breslow intermediate nor the NHC-aldehyde tetrahedral adduct) has been u... more Benzoin (and neither the Breslow intermediate nor the NHC-aldehyde tetrahedral adduct) has been unambiguously identified as the oxidised species in aerobic NHC-catalysed aldehyde esterifications.
A highly efficient, broad scope, additive-free mild protocol for the oxidative carbene-catalysed ... more A highly efficient, broad scope, additive-free mild protocol for the oxidative carbene-catalysed esterification of aldehydes (including the related aqueous oxidation to acids) has been developed.
Proceedings of the National Academy of Sciences of the United States of America, Jan 21, 2015
The vibrational theory of olfaction assumes that electron transfer occurs across odorants at the ... more The vibrational theory of olfaction assumes that electron transfer occurs across odorants at the active sites of odorant receptors (ORs), serving as a sensitive measure of odorant vibrational frequencies, ultimately leading to olfactory perception. A previous study reported that human subjects differentiated hydrogen/deuterium isotopomers (isomers with isotopic atoms) of the musk compound cyclopentadecanone as evidence supporting the theory. Here, we find no evidence for such differentiation at the molecular level. In fact, we find that the human musk-recognizing receptor, OR5AN1, identified using a heterologous OR expression system and robustly responding to cyclopentadecanone and muscone, fails to distinguish isotopomers of these compounds in vitro. Furthermore, the mouse (methylthio)methanethiol-recognizing receptor, MOR244-3, as well as other selected human and mouse ORs, responded similarly to normal, deuterated, and (13)C isotopomers of their respective ligands, paralleling ou...
It has been shown for the first time that relatively electron deficient triazolium pre-catalysts ... more It has been shown for the first time that relatively electron deficient triazolium pre-catalysts promote (at low loadings in the presence of base) highly chemoselective crossed acyloin condensation reactions between aldehydes and α-ketoesters to afford densely functionalized products incorporating a quaternary stereocentre of considerable synthetic potential. Hydroacylation pathways which have hitherto been dominant in these reactions can be completely avoided. The scope of the process is extraordinarily broad with respect to both coupling partners, and a preliminary study has established the principle that a high degree of stereochemical control over the reaction can also be exercised via the use of a chiral NHC precursor. It has also been shown for the first time that coupling of benzyl α-ketoesters with aldehydes followed by acylation and simple hydrogenolysis furnishes a product formally derived from the chemoselective 1 : 1 coupling of two different aliphatic aldehydes in high ...
ABSTRACT Triazolium salt TRB in combination with K2CO3 is an efficient catalyst for the coupling ... more ABSTRACT Triazolium salt TRB in combination with K2CO3 is an efficient catalyst for the coupling reaction of aliphatic or aromatic/heteroaromatic aldehydes with α-ketoesters.
ABSTRACT Sequential oxidative cleavage of cyclic 1,2-diones with water as the nucleophile and est... more ABSTRACT Sequential oxidative cleavage of cyclic 1,2-diones with water as the nucleophile and esterification of the resulting diol allows the synthesis of various diesters.
It has been shown for the first time that relatively electron deficient triazolium pre-catalysts ... more It has been shown for the first time that relatively electron deficient triazolium pre-catalysts promote (at low loadings in the presence of base) highly chemoselective crossed acyloin condensation reactions between aldehydes and α-ketoesters to afford densely ...
ABSTRACT The first organocatalytic aerobic oxidative cleavage of cyclic 1,2-diketones is reported... more ABSTRACT The first organocatalytic aerobic oxidative cleavage of cyclic 1,2-diketones is reported. The reaction occurs in either aqueous or alcoholic media and is promoted by a simple N-heterocyclic carbene catalyst derived from a 1,2,4-triazolium ion. No strong oxidants are required. The application of the process in a one-pot synthesis of a cyclic anhydride is also possible.
Benzoin (and neither the Breslow intermediate nor the NHC-aldehyde tetrahedral adduct) has been u... more Benzoin (and neither the Breslow intermediate nor the NHC-aldehyde tetrahedral adduct) has been unambiguously identified as the oxidised species in aerobic NHC-catalysed aldehyde esterifications.
A highly efficient, broad scope, additive-free mild protocol for the oxidative carbene-catalysed ... more A highly efficient, broad scope, additive-free mild protocol for the oxidative carbene-catalysed esterification of aldehydes (including the related aqueous oxidation to acids) has been developed.
Proceedings of the National Academy of Sciences of the United States of America, Jan 21, 2015
The vibrational theory of olfaction assumes that electron transfer occurs across odorants at the ... more The vibrational theory of olfaction assumes that electron transfer occurs across odorants at the active sites of odorant receptors (ORs), serving as a sensitive measure of odorant vibrational frequencies, ultimately leading to olfactory perception. A previous study reported that human subjects differentiated hydrogen/deuterium isotopomers (isomers with isotopic atoms) of the musk compound cyclopentadecanone as evidence supporting the theory. Here, we find no evidence for such differentiation at the molecular level. In fact, we find that the human musk-recognizing receptor, OR5AN1, identified using a heterologous OR expression system and robustly responding to cyclopentadecanone and muscone, fails to distinguish isotopomers of these compounds in vitro. Furthermore, the mouse (methylthio)methanethiol-recognizing receptor, MOR244-3, as well as other selected human and mouse ORs, responded similarly to normal, deuterated, and (13)C isotopomers of their respective ligands, paralleling ou...
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Papers by Sivaji Gundala