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Curt Wentrup - One of the best experts on this subject based on the ideXlab platform.
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Rearrangements of Acyl, Thioacyl, and Imidoyl (Thio)Cyanates to Iso(thio)Cyanates, Acyl Iso(thio)Cyanates to (Thio)acyl IsoCyanates, and Imidoyl Iso(thio)Cyanates to (Thio)acyl Carbodiimides, RCX-YCN ⇌ RCX-NCY ⇌ RCY-NCX ⇌ RCY-XCN (X and Y = O, S, NR′)
2016Co-Authors: Rainer Koch, Curt WentrupAbstract:Two types of rearrangements have been investigated computationally at the B3LYP/6-311+G(d,p) level. The activation barriers for rearrangement of acyl thioCyanates RCO–SCN to the corresponding isothioCyanates RCO–NCS are 30–31 kcal/mol in agreement with the observation that the thioCyanates are in some cases isolable albeit very sensitive compounds. Alkoxycarbonyl-, (alkylthio)carbonyl- and carbamoyl thioCyanates are isolable and have higher calculated barriers (ca. 40 kcal/mol) toward rearrangement to isothioCyanates, whereas all thioacyl thiocyanate derivatives are rather unstable compounds with barriers in the range 20–30 kcal/mol for rearrangement to the isothioCyanates. Acyl-, alkoxycarbonyl-, and carbamoyl Cyanates R–CO–OCN are predicted to be in some cases isolable compounds with barriers up to ca. 40 kcal/mol for rearrangement to the isoCyanates RCO–NCO. All of the rearrangements of this type involve the HOMO of a nearly linear (thio)cyanate anion and the LUMO of the acyl cation, in particular the acyl CX π* orbital. The second type of rearrangement involves 1,3-shifts of the groups R attached to the (thio)acyl groups, that is, acyl isothiocyanate–thioacyl isocyanate and imidoyl isothiocyanate–thioacyl carbodiimide rearrangements. These reactions involve four-membered cyclic, zwitterionic transition states facilitated by lone pair–LUMO interactions between the migrating R group and the neighboring iso(thio)cyanate function. Combination of the two rearrangements leads to the general reaction scheme RCX–YCN ⇌ RCX–NCY ⇌ RCY–NCX ⇌ RCY–XCN (X and Y = O, S, NR′)
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rearrangements of acyl thioacyl and imidoyl thio Cyanates to iso thio Cyanates acyl iso thio Cyanates to thio acyl isoCyanates and imidoyl iso thio Cyanates to thio acyl carbodiimides rcx ycn rcx ncy rcy ncx rcy xcn x and y o s nr
Journal of Organic Chemistry, 2013Co-Authors: Rainer Koch, Curt WentrupAbstract:Two types of rearrangements have been investigated computationally at the B3LYP/6-311+G(d,p) level. The activation barriers for rearrangement of acyl thioCyanates RCO-SCN to the corresponding isothioCyanates RCO-NCS are 30-31 kcal/mol in agreement with the observation that the thioCyanates are in some cases isolable albeit very sensitive compounds. Alkoxycarbonyl-, (alkylthio)carbonyl- and carbamoyl thioCyanates are isolable and have higher calculated barriers (ca. 40 kcal/mol) toward rearrangement to isothioCyanates, whereas all thioacyl thiocyanate derivatives are rather unstable compounds with barriers in the range 20-30 kcal/mol for rearrangement to the isothioCyanates. Acyl-, alkoxycarbonyl-, and carbamoyl Cyanates R-CO-OCN are predicted to be in some cases isolable compounds with barriers up to ca. 40 kcal/mol for rearrangement to the isoCyanates RCO-NCO. All of the rearrangements of this type involve the HOMO of a nearly linear (thio)cyanate anion and the LUMO of the acyl cation, in particular the acyl =X π* orbital. The second type of rearrangement involves 1,3-shifts of the groups R attached to the (thio)acyl groups, that is, acyl isothiocyanate-thioacyl isocyanate and imidoyl isothiocyanate-thioacyl carbodiimide rearrangements. These reactions involve four-membered cyclic, zwitterionic transition states facilitated by lone pair-LUMO interactions between the migrating R group and the neighboring iso(thio)cyanate function. Combination of the two rearrangements leads to the general reaction scheme RCX-YCN ⇌ RCX-NCY ⇌ RCY-NCX ⇌ RCY-XCN (X and Y = O, S, NR′).
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3 3 sigmatropic shifts and retro ene rearrangements in Cyanates isoCyanates thioCyanates and isothioCyanates of the form rx ycn and rx ncy
Journal of Organic Chemistry, 2012Co-Authors: Rainer Koch, Justin J Finnerty, Sukumaran Murali, Curt WentrupAbstract:Retro-ene type [2π + 2π + 2σ] and [3,3]-sigmatropic shift reactions involving the substituent groups R in heteroatom-substituted Cyanates and thioCyanates RX-YCN and the isomeric isoCyanates and isothioCyanates of the type RX-NCY (X = CR(2), NR', O, or S; Y = O or S) have been investigated computationally at the B3LYP/6-311++G(d,p) level. Retro-ene reactions of alkyl derivatives of the title compounds afford alkenes, imines, carbonyl and thiocarbonyl compounds together with HNCO (HNCS) or HOCN (HSCN). [3,3]-Sigmatropic shifts (hetero-Cope rearrangements) of the corresponding allyl, propargyl, benzyl, and aryl derivatives causes allylic rearrangements, propargyl-allenyl rearrangement, conversion of benzyl Cyanates to o-isocyanatotoluenes, and conversion of N-cyanatoarylamines to o-isocyanatoanilines, etc. The corresponding rearrangements of allyl thioCyanates, arylamino thioCyanates and isothioCyanates, and arylsulfenyl thioCyanates and isothioCyanates are also described.
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[3,3]-Sigmatropic Shifts and Retro-ene Rearrangements in Cyanates, IsoCyanates, ThioCyanates, and IsothioCyanates of the Form RX-YCN and RX-NCY
2012Co-Authors: Rainer Koch, Justin J Finnerty, Sukumaran Murali, Curt WentrupAbstract:Retro-ene type [2π + 2π + 2σ] and [3,3]-sigmatropic shift reactions involving the substituent groups R in heteroatom-substituted Cyanates and thioCyanates RX-YCN and the isomeric isoCyanates and isothioCyanates of the type RX-NCY (X = CR2, NR′, O, or S; Y = O or S) have been investigated computationally at the B3LYP/6-311++G(d,p) level. Retro-ene reactions of alkyl derivatives of the title compounds afford alkenes, imines, carbonyl and thiocarbonyl compounds together with HNCO (HNCS) or HOCN (HSCN). [3,3]-Sigmatropic shifts (hetero-Cope rearrangements) of the corresponding allyl, propargyl, benzyl, and aryl derivatives causes allylic rearrangements, propargyl–allenyl rearrangement, conversion of benzyl Cyanates to o-isocyanatotoluenes, and conversion of N-cyanatoarylamines to o-isocyanatoanilines, etc. The corresponding rearrangements of allyl thioCyanates, arylamino thioCyanates and isothioCyanates, and arylsulfenyl thioCyanates and isothioCyanates are also described
Rainer Koch - One of the best experts on this subject based on the ideXlab platform.
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Rearrangements of Acyl, Thioacyl, and Imidoyl (Thio)Cyanates to Iso(thio)Cyanates, Acyl Iso(thio)Cyanates to (Thio)acyl IsoCyanates, and Imidoyl Iso(thio)Cyanates to (Thio)acyl Carbodiimides, RCX-YCN ⇌ RCX-NCY ⇌ RCY-NCX ⇌ RCY-XCN (X and Y = O, S, NR′)
2016Co-Authors: Rainer Koch, Curt WentrupAbstract:Two types of rearrangements have been investigated computationally at the B3LYP/6-311+G(d,p) level. The activation barriers for rearrangement of acyl thioCyanates RCO–SCN to the corresponding isothioCyanates RCO–NCS are 30–31 kcal/mol in agreement with the observation that the thioCyanates are in some cases isolable albeit very sensitive compounds. Alkoxycarbonyl-, (alkylthio)carbonyl- and carbamoyl thioCyanates are isolable and have higher calculated barriers (ca. 40 kcal/mol) toward rearrangement to isothioCyanates, whereas all thioacyl thiocyanate derivatives are rather unstable compounds with barriers in the range 20–30 kcal/mol for rearrangement to the isothioCyanates. Acyl-, alkoxycarbonyl-, and carbamoyl Cyanates R–CO–OCN are predicted to be in some cases isolable compounds with barriers up to ca. 40 kcal/mol for rearrangement to the isoCyanates RCO–NCO. All of the rearrangements of this type involve the HOMO of a nearly linear (thio)cyanate anion and the LUMO of the acyl cation, in particular the acyl CX π* orbital. The second type of rearrangement involves 1,3-shifts of the groups R attached to the (thio)acyl groups, that is, acyl isothiocyanate–thioacyl isocyanate and imidoyl isothiocyanate–thioacyl carbodiimide rearrangements. These reactions involve four-membered cyclic, zwitterionic transition states facilitated by lone pair–LUMO interactions between the migrating R group and the neighboring iso(thio)cyanate function. Combination of the two rearrangements leads to the general reaction scheme RCX–YCN ⇌ RCX–NCY ⇌ RCY–NCX ⇌ RCY–XCN (X and Y = O, S, NR′)
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rearrangements of acyl thioacyl and imidoyl thio Cyanates to iso thio Cyanates acyl iso thio Cyanates to thio acyl isoCyanates and imidoyl iso thio Cyanates to thio acyl carbodiimides rcx ycn rcx ncy rcy ncx rcy xcn x and y o s nr
Journal of Organic Chemistry, 2013Co-Authors: Rainer Koch, Curt WentrupAbstract:Two types of rearrangements have been investigated computationally at the B3LYP/6-311+G(d,p) level. The activation barriers for rearrangement of acyl thioCyanates RCO-SCN to the corresponding isothioCyanates RCO-NCS are 30-31 kcal/mol in agreement with the observation that the thioCyanates are in some cases isolable albeit very sensitive compounds. Alkoxycarbonyl-, (alkylthio)carbonyl- and carbamoyl thioCyanates are isolable and have higher calculated barriers (ca. 40 kcal/mol) toward rearrangement to isothioCyanates, whereas all thioacyl thiocyanate derivatives are rather unstable compounds with barriers in the range 20-30 kcal/mol for rearrangement to the isothioCyanates. Acyl-, alkoxycarbonyl-, and carbamoyl Cyanates R-CO-OCN are predicted to be in some cases isolable compounds with barriers up to ca. 40 kcal/mol for rearrangement to the isoCyanates RCO-NCO. All of the rearrangements of this type involve the HOMO of a nearly linear (thio)cyanate anion and the LUMO of the acyl cation, in particular the acyl =X π* orbital. The second type of rearrangement involves 1,3-shifts of the groups R attached to the (thio)acyl groups, that is, acyl isothiocyanate-thioacyl isocyanate and imidoyl isothiocyanate-thioacyl carbodiimide rearrangements. These reactions involve four-membered cyclic, zwitterionic transition states facilitated by lone pair-LUMO interactions between the migrating R group and the neighboring iso(thio)cyanate function. Combination of the two rearrangements leads to the general reaction scheme RCX-YCN ⇌ RCX-NCY ⇌ RCY-NCX ⇌ RCY-XCN (X and Y = O, S, NR′).
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3 3 sigmatropic shifts and retro ene rearrangements in Cyanates isoCyanates thioCyanates and isothioCyanates of the form rx ycn and rx ncy
Journal of Organic Chemistry, 2012Co-Authors: Rainer Koch, Justin J Finnerty, Sukumaran Murali, Curt WentrupAbstract:Retro-ene type [2π + 2π + 2σ] and [3,3]-sigmatropic shift reactions involving the substituent groups R in heteroatom-substituted Cyanates and thioCyanates RX-YCN and the isomeric isoCyanates and isothioCyanates of the type RX-NCY (X = CR(2), NR', O, or S; Y = O or S) have been investigated computationally at the B3LYP/6-311++G(d,p) level. Retro-ene reactions of alkyl derivatives of the title compounds afford alkenes, imines, carbonyl and thiocarbonyl compounds together with HNCO (HNCS) or HOCN (HSCN). [3,3]-Sigmatropic shifts (hetero-Cope rearrangements) of the corresponding allyl, propargyl, benzyl, and aryl derivatives causes allylic rearrangements, propargyl-allenyl rearrangement, conversion of benzyl Cyanates to o-isocyanatotoluenes, and conversion of N-cyanatoarylamines to o-isocyanatoanilines, etc. The corresponding rearrangements of allyl thioCyanates, arylamino thioCyanates and isothioCyanates, and arylsulfenyl thioCyanates and isothioCyanates are also described.
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[3,3]-Sigmatropic Shifts and Retro-ene Rearrangements in Cyanates, IsoCyanates, ThioCyanates, and IsothioCyanates of the Form RX-YCN and RX-NCY
2012Co-Authors: Rainer Koch, Justin J Finnerty, Sukumaran Murali, Curt WentrupAbstract:Retro-ene type [2π + 2π + 2σ] and [3,3]-sigmatropic shift reactions involving the substituent groups R in heteroatom-substituted Cyanates and thioCyanates RX-YCN and the isomeric isoCyanates and isothioCyanates of the type RX-NCY (X = CR2, NR′, O, or S; Y = O or S) have been investigated computationally at the B3LYP/6-311++G(d,p) level. Retro-ene reactions of alkyl derivatives of the title compounds afford alkenes, imines, carbonyl and thiocarbonyl compounds together with HNCO (HNCS) or HOCN (HSCN). [3,3]-Sigmatropic shifts (hetero-Cope rearrangements) of the corresponding allyl, propargyl, benzyl, and aryl derivatives causes allylic rearrangements, propargyl–allenyl rearrangement, conversion of benzyl Cyanates to o-isocyanatotoluenes, and conversion of N-cyanatoarylamines to o-isocyanatoanilines, etc. The corresponding rearrangements of allyl thioCyanates, arylamino thioCyanates and isothioCyanates, and arylsulfenyl thioCyanates and isothioCyanates are also described
Tomislav Friscic - One of the best experts on this subject based on the ideXlab platform.
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mechanosynthesis of pharmaceutically relevant sulfonyl thio ureas
ChemInform, 2014Co-Authors: Davin Tan, Vjekoslav Strukil, Cristina Mottillo, Tomislav FriscicAbstract:The first application of mechanochemistry to conduct the synthesis of sulfonyl-(thio)ureas (III), (VI), and (X), including antidiabetic drugs tolbutamide, chlorpropamide (VIa) and glibenclamide (X) by either stoichiometric base-assisted or Cu-catalyzed coupling of sulfonamides and iso(thio)Cyanates, is reported.
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mechanosynthesis of pharmaceutically relevant sulfonyl thio ureas
Chemical Communications, 2014Co-Authors: Davin Tan, Vjekoslav Strukil, Cristina Mottillo, Tomislav FriscicAbstract:We demonstrate the first application of mechanochemistry to conduct the synthesis of sulfonyl-(thio)ureas, including known anti-diabetic drugs tolbutamide, chlorpropamide and glibenclamide, in good to excellent isolated yields by either stoichiometric base-assisted or copper-catalysed coupling of sulfonamides and iso(thio)Cyanates.
Davin Tan - One of the best experts on this subject based on the ideXlab platform.
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mechanosynthesis of pharmaceutically relevant sulfonyl thio ureas
ChemInform, 2014Co-Authors: Davin Tan, Vjekoslav Strukil, Cristina Mottillo, Tomislav FriscicAbstract:The first application of mechanochemistry to conduct the synthesis of sulfonyl-(thio)ureas (III), (VI), and (X), including antidiabetic drugs tolbutamide, chlorpropamide (VIa) and glibenclamide (X) by either stoichiometric base-assisted or Cu-catalyzed coupling of sulfonamides and iso(thio)Cyanates, is reported.
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mechanosynthesis of pharmaceutically relevant sulfonyl thio ureas
Chemical Communications, 2014Co-Authors: Davin Tan, Vjekoslav Strukil, Cristina Mottillo, Tomislav FriscicAbstract:We demonstrate the first application of mechanochemistry to conduct the synthesis of sulfonyl-(thio)ureas, including known anti-diabetic drugs tolbutamide, chlorpropamide and glibenclamide, in good to excellent isolated yields by either stoichiometric base-assisted or copper-catalysed coupling of sulfonamides and iso(thio)Cyanates.
Barry K Sharpless - One of the best experts on this subject based on the ideXlab platform.
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an intramolecular 2 3 cycloaddition route to fused 5 heterosubstituted tetrazoles
Organic Letters, 2001Co-Authors: Zachary Demko P And, Barry K SharplessAbstract:Fused 5-heterotetrazole ring systems are synthesized in high yield via intramolecular [2 + 3] cycloadditions of organic azides and heteroatom-substituted nitriles. Cyanates, thioCyanates, and cyanamides are all competent dipolarophiles for this reaction. A variety of scaffolds are tolerated when the new enclosed ring is five- or six-membered.
