TBHP/I₂-Mediated Domino Oxidative Cyclization for One-Pot Synthesis of Polysubstituted Oxazoles

Abstract

A facile type of one-pot, transition-metal-free domino process was developed for the synthesis of oxazoles. Thus, a variety of polysubstituted oxazoles were easily synthesized via t-BuOOH/I(2)-mediated domino oxidative cyclization from readily available starting materials under mild conditions.

Iodine-mediated synthesis of 3-acylbenzothiadiazine 1,1-dioxides

“…On the basis of this experiment described above and literature [13,35–36], a possible mechanism was proposed in Scheme 7. The halogenation of 1a with iodine results in the formation of compound A , which, via Kornblum oxidation, provides phenylglyoxal B .…”

Room Temperature Copper(II)-Catalyzed Oxidative Cyclization of Enamides to 2,5-Disubstituted Oxazoles via Vinylic C–H Functionalization

“…= 109-111 °C). 39 1 H NMR (400 MHz, CDCl 3 ) δ: 8.14 (d, J = 8.0 Hz, 2H), 7.69-7.65 (ovrlp, 4H), 7.43-7.39 (ovrlp, 3H), 7.32 (t, J = 7.6 Hz, 1H). 13 C NMR (100 MHz, CDCl 3 ) δ: 159.7, 152.1, 131.8 (q, 2 J CF = 32.6 Hz), 130.6, 129.0, 128.9, 127.7, 126.4, 125.9 (q, 3 J CF = 3.5 Hz), 124.4, 124.0 (q, 1 J CF = 270.7 Hz), 123.8.…”

“…: 78-79 °C). 39 1 H NMR (400 MHz, CDCl 3 ) δ: 8.07 (d, J = 8.0 Hz, 2H), 7.59 (d, J = 8.8 Hz, 2H), 7.46-7.38 (ovrlp, 3H), 7.29 (s, 1H), 6.92 (d, J = 8.8 Hz, 2H), 3.77 (s, 3H). 13 C NMR (100 MHz, CDCl 3 ) δ: 160.5, 159.8, 151.3, 130.1, 128.8, 127.6, 126.1, 125.7, 121.9, 120.8, 114.4, 55.3.…”

Halogens

“…26 A combination of arylalkenes and benzylic amines are readily converted to polysubstituted oxazoles via a one-pot tert-BuOOH/I 2 mediated oxidative cyclization. 27 Switchable access to dihydropyrazoles and pyrazoles from common hydrazides is effected through controlling the oxidative aromatization in iodocyclization. 28 Use of I(2,4,6-collidine) 2 PF 6 affords dihydropyrazoles while N-iodosuccinimide affords pyrazoles derived from the same hydrazide.…”