Terminal Alkyne-Assisted One-Pot Synthesis of Arylamidines: Carbon Source of the Amidine Group from Oxime Chlorides

Abstract

A terminal alkyne-assisted protocol for the one-pot formation of a diverse range of arylamidines from a novel cascade reaction of in situ generated nitrile oxides, sulfonyl azides, terminal alkynes, and water by [3 + 2] cycloaddition and ring opening sequence was developed. The use of aryl oxime chlorides as the carbon source of the amidine group and the addition of water proved to be critical for the reaction. Moreover, terminal alkynes, which can lead to high yields of products by employing a less amount, may play a catalytic role in the reaction. A broader range of substrates was investigated.

Facile Synthesis of Tricyclic 1,2,4-Oxadiazolines-Fused Tetrahydro-Isoquinolines from Oxime Chlorides with 3,4-Dihydroisoquinoline Imines

“…To optimizethe reaction conditions, we initially attempted to react 3,4-dihydroisoquinoline 2a with in-situ-generated nitrile oxide via dehydrochlorination of the phenylhydroximoyl chloride 1a . The phenylhydroximoyl chloride 1a has extensive utility in 1,3-dipolar cycloadditions for the synthesis of a wide variety of important heterocycle compounds, which could generate nitrile oxides in situ in the presence of base [ 33 , 34 , 35 , 36 , 37 , 38 , 39 ]. Gratifyingly, the tricyclic 1,2,4-oxadiazolines-fused tetrahydro-isoquinoline 3a was formed in 72% isolated yield in the presence of 1,4-diazabicyclo[2.2.2]octane (DABCO) in CH 2 Cl 2 at room temperature for 12 h (entry 1, in Table 1 ) via [3 + 2] 1,3-dipolar cycloaddition reaction.…”

Recent advances in the application of alkynes in multicomponent reactions

“…47 Scheme 29 Synthesis of arylamidines 69 from oxime chlorides. 52 Jin and co-workers 55 synthesized 2,3-dihydro-1H-imidazo[1,2a]indole derivatives 80 via the reaction among allylamine derivatives 79, sulfonyl azide derivatives 78, and alkyne derivatives 77 (Scheme 35). In the rst step, triethylamine (Et 3 N) as a base and CuI as a catalyst were added to the mixture in DMSO at room temperature for 1 h. Aer that, L1, K 2 CO 3 , and CuI were added to the mixture and heated at the temperature of 80 °C for 6 h.…”

Advances in the Synthesis of N-Sulfonyl Amidines

“…胡跃飞等 [44] 此外, 易维银等 [49] 以碘化亚铜为催化剂, 在碱性条 件和室温下于二氯甲烷水溶液中搅拌, 磺酰叠氮和氯化 肟反应合成了 NH 2 官能化 N-磺基脒. 反应采用端炔作 为辅助物促进反应.…”