Unprecedented 1,3-tert-butyl migration via the C–N single bond scission of isonitrile: an expedient metal-free route to N-sulfonyl amidines

Abstract

Treatment of tert-butyl isonitrile with ArSO2NBr2 and nitrile led to simultaneous C–N single bond scission of isonitrile and migration of tert-alkyl group to nitrogen centre of the nitrile precursor, resulting in the formation of N-sufonyl amidine.

Cascade Synthesis of 5-Aminotetrazoles from Isonitriles and N,N-Dibromoarylsulfonamides via Carbodiimide Coupling with Azide

“…Following the general procedure, compound 5k was prepared from benzyl isocyanide (61 μL), N,N-dibromo-4-nitrobenzenesulfonamide (179 mg), sodium azide (65 mg), and BTAB (115 mg) in the presence of K 2 CO 3 (2 equiv, 138 mg). Purified by column chromatography on silica gel (Petroleum ether/EtOAc = 1:1); colorless semisolid (66%, 119 mg); 1 H NMR (DMSO-d 6 , 600 MHz): δ 7.73 (d,J = 6 Hz,2H),7.57 (d,J = 7.8 Hz,2H),7.35(br. s,1H),7.29 (d,J = 7.2 Hz,2H),7.21 (t,J = 5.4 Hz,2H),4,41 (d,J = 5.4 Hz,2H); 13 C{ 1 H} NMR (DMSO-d 6 , 150 MHz): δ 156.…”

“…Following the general procedure, compound 5g was prepared from 1-ethyl-2-isocyano-3-methylbenzene (73 μL), N,N-dibromo-p-toluenesulfonamide (164 mg), sodium azide (65 mg), and BTAB (115 mg) in the presence of K 2 CO 3 (2 equiv, 138 mg). Purified by column chromatography on silica gel (Petroleum ether/EtOAc = 1:1); Black liquid (76%, 135 mg); 1 H NMR (DMSO-d 6 , 600 MHz): δ 7.72 (d,J = 7.8 Hz,2H),1H),4H), 2.33 (s, 3H), 2.20−2.08 (m, 2H), 1.82 (s, 3H), 0.93 (t, J = 7.6 Hz, 3H); 13 C{ 1 H} NMR (DMSO-d 6 , 150 MHz): δ 154. 1, 141.8, 141.2, 140.9, 136.1, 131.8, 130.2, 128.7, 128.2, 126.8, 126.7, 23.8, 20.9, 17.1, 14.4 143.0, 139.5, 136.7, 128.5, 128.3, 127.6, 126.6, 46.9, 20.9 -(2,4,4-trimethylpentan-2-yl)-1H-tetrazol-5amine (5i).…”

“…Following the general procedure, compound 4j was prepared from tert-butyl isocyanide (57 μL), N,N-dibromo-2trifluoromethylbenzenesulfonamide (191 mg), sodium azide (65 mg), and BTAB (115 mg) in the presence of K 2 CO 3 (2 equiv, 138 mg). Purified by column chromatography on silica gel (Petroleum ether/EtOAc = 1:1); colorless semisolid (65%, 113 mg); 1 H NMR (DMSO-d 6 , 600 MHz): δ 8.26 (d,J = 7.8 Hz,1H),7.72 (d,J = 7.8 Hz,1H),7.67 (d,J = 7.2 Hz, 1H), 7.58 (t, J = 7.2 Hz, 1H), 1.57 (s, 9H); 13 C{ 1 H} NMR (DMSO-d 6 , 150 MHz): δ 155. 1,144.7,131.6,130.1,126.9,125.7 (J CF = 30.7 Hz),124.4,122.6,57.5,27.8; IR (KBr, cm −1 ): ν 3371, 2957,1588,1493,1143; HRMS m/z (ESI) calculated for C 12 H 14 F 3 N 5 O 2 SNa (M+Na) + 372.0713, found 372.0711.…”

A Unified Approach for the Synthesis of Isourea and Isothiourea from Isonitrile and N,N-Dibromoarylsulfonamides

“…In continuation of our work on N,N -dibromoaryl­sulfonamides for various organic transformations, we developed an efficient methodology for carbodiimide coupling reactions for the synthesis of guanidines and amidines. , We speculated that, under appropriate conditions, if carbodiimide can be coupled with alcohols or thiols, this may provide a generalized and versatile strategy for the synthesis of both isourea and isothiourea in a unified approach. Within this manuscript, we show that alcohols or thiols can efficiently react with N,N -dibromoaryl­sulfonamides and isonitrile in a three-component coupling procedure to produce corresponding isourea or isothiourea respectively in a robust manner under metal-free conditions.…”

Catalyst-free one-pot, four-component approach for the synthesis of di- and tri-substitutedN-sulfonyl formamidines

“… 11 Additionally, Bi and co-workers 12 described a silver-catalyzed, one-pot, four-component reaction involving terminal alkynes reacting directly with trimethylsilyl azide (TMSN 3 ), sodium sulfinate, and sulfonyl azide ( Scheme 1c ). Phukan et al 13 described a metal-free strategy for the synthesis of di-substituted sulfonyl amidines via a one-pot reaction between tert -butylisonitrile and N , N -dibromoaryl sulfonamides in the presence of a nitrile compound in aqueous media ( Scheme 1d ), and other groups have applied similar methods. 14 However, most protocols still typically require special reagents, including transition metal catalysts or expensive and potentially explosive sulfonyl azides, and they often proceed at elevated temperatures.…”