AgNTf2-catalyzed formal [3+2] cycloaddition of ynamides with unprotected isoxazol-5-amines: efficient access to functionalized 5-amino-1H-pyrrole-3-carboxamide derivatives was written by Cao, Ziping;Zhu, Jiekun;Liu, Li;Pang, Yuanling;Tian, Laijin;Sun, Xuejun;Meng, Xin. And the article was included in Beilstein Journal of Organic Chemistry in 2019.Formula: C7H12N2O This article mentions the following:
A formal [3 + 2] cycloaddition between ynamides RCCN(R1C6H5)R2 (R = H, 2-Me, 4-F, 3-Me, etc.; R1 = Me, Bn, Ph, etc.; R2 = Ts, Ms, o-Ns, p-Ns) and unprotected isoxazol-5-amines I (R3 = Me, Ph, i-Pr, etc.) has been developed in the presence of catalytic AgNTf2 in an open flask. By the protocol, a variety of functionalized 5-amino-1H-pyrrole-3-carboxamide derivatives II can be obtained in up to 99% yield. The reaction mechanism might involve the generation of an unusual alpha-imino silver carbene intermediate (or a silver-stabilized carbocation) and subsequent cyclization/isomerization to build the significant pyrrole-3-carboxamide motif. The reaction features the use of an inexpensive catalyst, simple reaction conditions, simple work-up without column chromatog. purification for most of products and high yields. In the experiment, the researchers used many compounds, for example, 3-(tert-Butyl)isoxazol-5-amine (cas: 59669-59-9Formula: C7H12N2O).
3-(tert-Butyl)isoxazol-5-amine (cas: 59669-59-9) belongs to isoxazole derivatives. An isoxazolyl group is found in many beta-lactamase-resistant antibiotics, such as cloxacillin, dicloxacillin and flucloxacillin. Fe(CO)5 efficiently cleaves the N–O bond of fused isoxazolo-1,4-quinones to give the corresponding imines.All the common reducing reagents failed to open the isoxazole ring.Formula: C7H12N2O
Referemce:
Isoxazole – Wikipedia,
Isoxazole | C3H3NO – PubChem