Rhodium-Catalyzed Transannulation of 4,5-Fused 1-Sulfonyl-1,2,3-triazoles with Nitriles. The Selective Formation of 1-Sulfonyl-4,5-fused Imidazoles versus Secondary C–H Bond Migration

Abstract

The reactivity of readily available 4,5-fused-1-sulfonyl-1,2,3-triazoles was examined in the Rh­(II)-catalyzed transannulation reaction with nitriles. We have come across the interesting observation that 1-sulfonyl cycloalkeno­[d]­[1,2,3]­triazoles that possess β-hydrogens resist intramolecular β-hydride migration and could serve as a new source of Rh-iminocarbenoids for intermolecular Rh­(II)-catalyzed transannulation reactions. As a result, 1-sulfonyl cyclohexeno-, cyclohepteno-, dihydropyrano-, 5-phenyltetrahydrobenzo-, and 4,5-dihydronaphtho­[d]­imidazoles were synthesized from various nitriles in good yields. A one-pot methodology has also been executed for the synthesis of NH-imidazoles.

I2-DMSO-Mediated Transannulation of Benzo[d]isoxazol-3-amine: Direct Access to 2,4,5-Substituted Pyrimidine Derivatives

“…Yield 63%; 266.0 mg; yellow solid; mp 195−196 °C; TLC (15:1 PE/EtOAc, v/v) R f = 0.3; 1 H NMR (400 MHz, CDCl 3 ) δ 12.46 (s, 1H), 9.01 (s,1H),8.46 (d,J = 8.0 Hz,1H),7.96 (d,J = 7.6 Hz,2H),7.75 (d,J = 8.0 Hz,2H),7.63 (t,J = 7.2 Hz,1H),3H),7.32 (d,J = 8.0 Hz,2H),7.02 (d,J = 8.4 Hz,1H),6.94 (t,J = 7.6 Hz,1H),2.96 (dt,J = 13.6,6.8 Hz,1H),1.26 (d,J = 6.8 Hz,6H); 13 C{ 1 H} NMR (100 MHz, CDCl 3 ) δ 191. 6,191.5,165.0,164.4,161.1,156.7,155.9,134.7,134.3,134.2,133.7,130.3,130.1,130.0,128.7,127.0,119.5,118.2,117.8,34.3,23.5;HRMS (ESI) 6, 191.5, 165.0, 164.5, 161.1, 158.0, 156.7, 134.7, 134.3, 134.2, 133.2, 130.3, 130.0, 129.8, 128.7, 128.6, 125.9, 119.5, 118.2, 117.8, 35.2, 30.9…”

“…9,129.7,128.9,128.1,126.2 (d,J = 3.0 Hz,4 J CF ), 121.3 (d, J = 22.0 Hz, 2 J CF ), 119. 6,118.2,117.6,116.5 (d,J = 23.0 Hz,2 8, 189.2, 165.5, 164.7, 162.0 (d, J = 255.0 Hz, 1 J CF ), 161.0, 157.1, 136.1 (d, J = 9.0 Hz, 3 J CF ), 135.8,134.7,133.8,131.1,129.9,129.5,128.8,126.4,124.7 (d,J = 3.0 Hz,4 J CF ), 123.2 (d, J = 11.0 Hz, 2 J CF ), 119. 4, 118.1, 117.7, 116.4 [ pyrimidin-4-yl](4-chlorophenyl)methanone (4s).…”

“…5 Despite these valuable achievements, the development of a metal-free transannulation reaction employing multiple components could enrich the reactivity and application of benzo [d]isoxazol-3-amine and remains a challenge. 6 On the basis of our continuous interest in I 2 -DMSOmediated multicomponent reactions for the synthesis of heterocyclic compounds, herein, we present a mild and metal-free three-component cascade annulation reaction with readily available materials for accessing 2,4,5-substituted pyrimidine derivatives (Scheme 1d). 7 This [3+1+2] annulation reaction involved the transannulation of benzo [d]isoxazol-3-amine and the construction of two C−N bonds and a C−C bond.…”

Arylethanolamines in Ritter reaction: Synthesis of 2,4‐Diarylimidazole Core

“…These heterocycles were also applied as ligands [11,12] and directing groups [13] in synthetic organic chemistry. A significant number of articles concerns the synthesis of 2,4‐diaryl substituted imidazolines [14] and imidazoles [15,16] . Among them, classic approaches reported by Casey and Khvat applied a consequent synthesis with a late stage cyclization of amidine or diamine (Figure 1a,b).…”

“…A significant number of articles concerns the synthesis of 2,4-diaryl substituted imidazolines [14] and imidazoles. [15,16] Among them, classic approaches reported by Casey and Khvat applied a consequent synthesis with a late stage cyclization of amidine or diamine (Figure 1a,b). [17,18] A copper-catalyzed aliphatic CÀ H amination at the benzylic position leading to cyclization of N-phenethylamidines was proposed by Chiba (Figure 1c).…”