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18.16.20.3.1 Synthesis of 2,2-Dialkoxy-2,5-dihydro-1,3,4-oxadiazoles from Ketone Hydrazones by Oxidative Cyclization

DOI: 10.1055/sos-SD-118-00435

Kantlehner, W.Science of Synthesis Knowledge Updates, (20144359.

Oxadiazoles 40 are prepared from N-methoxycarbonyl-substituted ketone hydrazones 39 and lead(IV) acetate (Scheme 17);[‌30‌‌33‌] they are generally isolated as a mixture with diazene 41 and used directly in the next reaction.[‌32‌,‌33‌] Investigation of the mechanism and the stereochemistry of the products has been undertaken,[‌32‌,‌33‌] and, in one case, the trans and cis isomers have been separated (Scheme 17).[‌32‌]

Meeeee 88 Meeeeeeee ee M-Meeeeeeeeeeeeee-Meeeeeeeeee Meeeee Meeeeeeeee[‌88‌‌88‌]

Meeeeeeeeee 88

M8 M8 Meeeeeeeee Meeee (88/88) Meeee (%) Mee
8-MeMM8M8 Me MeMM 8:8 88 [‌88‌]
Me Me MeMM, MM8Me8 8:8 88 [‌88‌]
8-MeMM8M8 Me MM8Me8 8:8 88 [‌88‌]

Meee eeeeeeeee eeee (eeeeeeeeee) eeeee eeeeeee 88, eee eeeee eeeeeee ee 8-eeeeeee-8-eeeeeee-8,8-eeeeeee-8,8,8-eeeeeeeeeee eee eeeeeee eeeee eee eeeeeeee-eeeeeeeeeee eeeeeeeeeee 88 (Meeeee 88).[‌88‌]

Meeeee 88 Meeeeeeeeee ee eee Meeeeee Meeee ee 8-Meeeeee-8-eeeeeee-8,8-eeeeeee-8,8,8-eeeeeeeeeee[‌88‌]

Meeeeeeeeee 88

M8 M8 Meeeeeeeee Meeeee (%) Mee
Me M MeMM, ee, 8 e 88–88 [‌88‌]
Me M MeMM, ee, 8 e 88–88 [‌88‌]
8-MeMM8M8 M ee, 8 e 88 [‌88‌]
8-MeMM8M8 M ee, 8 e 88 [‌88‌]

e Meeee eeee eee eeeeeeeeeeeeeeeeeeee eee eeeeeeee ee e eeeee eeeeeee ee eeeeeeeeee eee eeeeeee eeeeeeee.

8-Meeeeee-8-eeeeeee-8,8-eeeeeeee-8,8-eeeeeee-8,8,8-eeeeeeeeee (88) eeeeee eeee eeeee, ω-eeeeeeeeeee eeeeeeee, eeeeeeeeeee, eee eeeeeeee ee eeee eee eeeeeeeeeeeee 8-eeeeee-8-eeeeeeeeeeeeeeeeee 88 ee eeeeeeeeeeee ee eee eeeeeee eeeee. Mee eeeee eeeeeee eeee eee eeeeeeee ee eeeeee 8-eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee eeee eeee(MM) eeeeeee ee eeee 88 eee eeeeee 8-(8-eeeeeee-8-eeeeeeeeeee)eeeeeee-8-eeeeeeeeeee (88% eeeee, eeeee 8:8) ee eeeeeee eeee eeeeeeeeeeeeeee eeee eee eee eeeeeee ee eeeeeeeeeeeeeee (Meeeee 88).[‌88‌] Mee ω-eeeeeeeeeee 8-eeeeeeee-, 8-eeeeeeeeeee-, eee 8-eeeeeeee-8-eeeeeee-8,8-eeeeeeee-8,8-eeeeeee-8,8,8-eeeeeeeeeee eee eeeeeeeee ee eeeeeee eeeeeeeeee eeeee eeeeeeeeeeeee eeee ee Meeeee eee Meeeee–Meeeeeeee–Meeeee eeeeeeeee, eeeee eeeeeeeeee, eee eeeeeeeee ee eeeeeeee, eee.

Meeeee 88 Meeeeeeeeee ee 8-Meeeee-8-eeeeeee-8,8-eeeeeee-8,8,8-eeeeeeeeeee ee Meeeeeeeeeee ee ee Meeeeee Meeee[‌88‌]

Meeeeeeeeee 88

M8 Meeeee (%) Mee
88 [‌88‌]
88 [‌88‌]
88 [‌88‌]
88 [‌88‌]
88 [‌88‌]
88 [‌88‌]

e Meeee eeee eee eeeeeeeeeeeeeeeeeeee eee eeeeeeee ee e eeeee eeeeeee ee eeeeeeeeee eee eeeeeee eeeeeeee.

Me eeeeeee ee eeeee eeeeeeeee, eeeeeeeee ee 88 eeee eeeeee ee eee eeeeeeee ee ee eeee eeeeeee ee eeeeeeeeeee ee eee eeeeeee eeeee ee ee eeeeeeee eeeee ee eeee eeeeeeee 88 (Meeeee 88).[‌88‌]

Meeeee 88 Meeeeeeeeeee ee eee Meeeeee Meeee ee 8-Meeeeee-8-eeeeeee-8,8-eeeeeeee-8,8-eeeeeee-8,8,8-eeeeeeeeee ee e Meeeeeeeeeee Meeee[‌88‌]

Meeeeeeeeee 88

M8 M8 Meeee (%) Mee
Me Me ~88 [‌88‌]
Me Me ~88 [‌88‌]
Me M ~88 [‌88‌]
Me Me ~88 [‌88‌]
Me Me ~88 [‌88‌]
Me Me ~88 [‌88‌]
~88 [‌88‌]
88–88 [‌88‌]
(MM8)8 ~88 [‌88‌]
(MM8)8 ~88 [‌88‌]

Meeeeeeeeee eeeeeeeeee 88[‌88‌,‌88‌] eee eeeeeeee eeeeeeeeee 88[‌88‌] eee eee eeeeeeee eeee M-(ω-eeeeeeeeeeeee)eeeeeeee eeeeee eeeeeeeee 88 ee 8-eeeeeeeeeeee eeeeee eeeeee M-eeeeeeeeeeeeeeeeeeeeeeee (88), eeeeeeeeeeee, eee eeee ee eeeeeeee eeeeeeeee (Meeeee 88).

Meeeee 88 Meeeeeeeeeeee Meeeee eeee M-Meeeeeeeeeeeee-Meeeeeeeeee Meeeee Meeeeeeeee[‌88‌‌88‌]

Meeeeeeeeeee Meeeeeeee

8-Meeeeee-8-eeeeeee-8,8-eeeeeeee-8,8-eeeeeee-8,8,8-eeeeeeeeee (88, M8 = Me; M8 = Me) eee Meeeee 8-(8-Meeeeeeeeeeee-8-ee)eeeeeee-8-eeeeeeeeeee (88, M8 = Me):[‌88‌]

M eeeeeeeeee ee Me(MMe)8 (88.8 e, 888 eeee) eee MeMM (8.88 eM, 88 eeee) ee MM8Me8 (88 eM) eee eeeeee ee 8 °M ee e eeeee-eeeeee eeeee eeeeeeee eeee e eeeeeeeeee eeeeeee. M eeee ee eee eeeeeeeee-8-eeeeeeeeeee 88 (M8 = Me; 88.8 e, 888 eeee) ee MM8Me8 (88 eM) eee eeeee eee eeeeeee eeee 8 e. Mee eeeeee eeeeeee eee eeeeeee ee eeee ee ee, eeeeeee eee ee eeeeeeeeee 8 e, eee eeeeeeee eeeeeee Meeeee. Mee. ee MeMMM8 (~888 eM) eee eeeee ee eee eeeeeeee eeeee eM 8–8, eee eee eeeeee eeee eeeeeeeee, eee eee eeeee eeeeeee eeeee eee eeeeeeeee eeee MM8Me8 (8 × 88 eM). Mee eeeeeeee eeeeeee eeeeee eeee eeeee (MeMM8) eee eeeeeeeeeeee eeeee eeeeeee eeeeeeee. Mee eeeee eeeeeee (88.8 e, 88%), ee eeeee 8M MMM eeeeeeee eeeeee eee eeeeeeee ee eeeeeeeeee 88 eee eee eeeeeee 88 ee e 8:8 eeeee, eee eeee ee eeee ee eeeeeeeeee eeeeeeeee. Mee eeeeeeee eeeeeeee, ee eeeeeee ee eee eeeee eeeeeee eee eeeeeeee ee eeeee eeeeeeeeeeeeee (eeeeee eee, MeMMe/eeeeeee 8:88 ee 8:88) ee eeee eeee eeeeeeeeee 88 eee eee eeeeeeeeeeeeeeeeee 88 ee eeeeeeeee eee eeeeee eeee, eeeeeeeeeeee.

8-{[(M)-8-Meeeeeee-8-eeee]eee}-8-eeeeeee-8,8-eeeeeeee-8,8-eeeeeee-8,8,8-eeeeeeeeee [88, M8 = (M)-MM8MM=MMM]; Meeeeee Meeeeeeee:[‌88‌]

M eeee ee eeeeeeeeee 88 [88% e/e (8:8 eeeee ee 88/88, M8 = Me; M8 = Me), 8.88 e, 8.88 eeee] ee MM8Me8 (88 eM) eee eeeeeee eeeee eee eeeeeee ee e eeee ee 8-eeeeeeee-8-ee-8-ee (8.88 e, 8.88 eeee) eee MMM (88 ee, 8.88 eeee) ee MM8Me8 (8 eM). Mee eeeeeee eee eeeeeee ee ee eee 88 eee eee eee. ee MeMMM8 eee eeeee. Mee eee eeeeee eeee eeeeeeeee eee eee eeeeeee eeeee eee eeeeeeeee eeee MM8Me8 (8 × 88 eM). Mee eeeeeeee eeeeeee eeeeee eeee eeeee (eeeee MeMM8) eee eeeeeeeeeeee eeeee eeeeeee eeeeeeee. Mee eeeee eeeeeee eee eeeeeeee ee eeeee eeeeeeeeeeeeee (eeeeee eee, MeMMe/eeeeeee 8:88 ee 8:88) ee eeee eee eeeeeee ee e eeeeeeeee eee; eeeee: 8.88 e (88%).

References


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