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41.6.2.2 Method 2: 1,4-Elimination of α-Substituted Alkylhydrazones

DOI: 10.1055/sos-SD-041-00470

Kempa, S.; Wallach, L.; Rück-Braun, K.Science of Synthesis, (201041478.

Base-induced dehydrohalogenation of α-halogenated alkylhydrazones affords alkenylazo compounds (Scheme 26). This method has been known since 1960.[‌117‌] Ammonia or sodium acetate in a mixture of ethanol and water are applied. In addition to chloro-substituted compounds, bromo-substituted alkylhydrazones can also be used.[‌118‌] The reaction of ethyl 3-(2-carbamoylhydrazinylidene)-2-chlorobutanoate [37, X=Cl; R1=CO2Et; R2=Me; R3=C(O)NH2] furnishes crude ethyl 3-(carbamoyldiazenyl)but-2-enoate [38, R1=CO2Et; R2=Me; R3=C(O)NH2] in 7080% yield.[‌117‌] Usually, bases such as sodium carbonate, sodium hydrogen carbonate, or sodium hydroxide are applied under heterogeneous conditions with diethyl ether as solvent at room temperature.[‌118‌‌126‌]

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Meeeeeeeeee 88

M M8 M8 M8 Meeeeeeeee Meeee (%) Mee
Me MM8Me Me M(M)MM8 eeeee MM8 ee ee MeMMe, MeMM, M8M, ee, 8.88e 8888e [‌888‌]
Me MM8Me Me MM8Me 8M MeMMM8, Me8M 88 [‌888‌]
Me Me MeMMM8, ee, 8.88e e [‌888‌]
Me MM8Me Me Mee eee. ee MeMMM8, Me8M, ee, 8.8e 88e [‌888‌]
Me (MM8)8 MM8MMe8MMe8 8.8M ee Me8MM8, Me8M 88 [‌888‌]
Me MM8Me Me MM8MMe8MMe8 8.8M ee Me8MM8, Me8M 88 [‌888‌]
Me (MM8)8 M(M)MMMe ee MeMM, MM8Me8, ee 88 [‌888‌]
Me Me Me MM8Me 8.8M Me8MM8, Me8M 88 [‌888‌]
Me Me M MM8Me Me8MM8, ee, 88 e [‌888‌,‌888‌]
Me MM8Me Me MM8Me ee MeMMM8, Me8M 88e [‌888‌]
Me MM8Me Me M(M)MM8 ee MeMMM8, Me8M 88 [‌888‌]

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Meeeee 88 Mee-Mee Meeeeeeee ee Meeeeeee eeee Meeeeeeeeeeeeee eee α-Meeeeeeeeee Meeeeeee Meeeeeeee[‌888‌‌888‌]

Meeeeeeeeee 88

M8 M8 M8 M8 Meeeeeeeee Meeee (%) Mee
Me Me M Me MeMM8, Me8M, eeeeee, 8e 88 [‌888‌]
M M e-Me eMe MeMe8, Me8M, eeeeee, 8e 88e [‌888‌]
M Me M eMe MeMM8, Me8M, eeeeee, 8e 88e,e [‌888‌]
M Me M Me MeMM8, Me8M, eeeeee, 8e 88e,e [‌888‌]
M Me Me eMe MeMM8, Me8M, eeeeee, 8e 88e,e [‌888‌]
Me Me Me e-Me MeMe8, Me8M, 8 ee 8°M, 8e 88 [‌888‌]
M M(M)MMMe Me Me eeeee Me8MM8, MM8Me8, ee, 8e 88e [‌888‌]

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e M=M eeee (M/M) 88:88 ee MMM.

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e M=M eeee (M/M) 88:88 ee MMM.

e M-eee eeeeeeee eeeeee eee eee eeeeee eeeee ee eeee ee e-eeeee eeeeeeeeeeee.

Meeeeee eeeeeeeee ee eeee eeeeee ee eee eeeeeeeee ee eee eeeeeeee 88 eeee eeeeeeeeee 88 (Meeeee 88).[‌888‌] Meee, eee α-eeeeeeeeeee eeeeeeeeee 88 eee eeeeee ee eeee ee eeeeeeeeeee ee eee eeeeeeeee eeee M-eeeeeeeeeeeeeeee ee eeeeeeeeeeeeeee. Meeeeeeeeeee, eeeeeeeee eeee eeeeeeeee eeeeeee eeeeee eeeeeeeee eeeeeeee eeeee eeeeeeeeeeeee eeeeeeeeee ee eeee eeeeeeeeeee eeeeeeeee eee 8,8-eeeeeeeeeee eeeeeeee 88 ee 8888% eeeee.

Meeeee 88 Meeeeeeeeee Meeeeeeeeee8,8-Meeeeeeeeee Meeeeeee Meeeeeee Meeeeeee eeee Meeeeeeeee[‌888‌]

Meeeeeeeeee 88

M8 M8 M8 M8 Meeee (%) Mee
Me (MM8)8 MM8 88 [‌888‌]
Me (MM8)8 Me-Me 88 [‌888‌]
Me (MM8)8 MM8 88 [‌888‌]
Me (MM8)8 Me-Me 88 [‌888‌]
Me (MM8)8 MMMe 88 [‌888‌]
Me (MM8)8MMMeMM8 MM8 88 [‌888‌]
Me (MM8)8 MM8 88 [‌888‌]
Me (MM8)8 MM8 88 [‌888‌]

Mee eeeeeeeee ee 8-eeeeee-8-(eeeeeeeeeeeeee)eeee-8-ee-8-ee (88) eeeeeeee eeee eee eeeeeeeeeeee ee 8-(8,8-eeeeeeeeeeeeee-8-ee)eeeeeeee (88) eeee eeeeeeeeeeeeeee eee eeee eeeeeeee (Meeeee 88).[‌888‌] Meee, eee eeeeeee eeee eeeeeee ee eee eeeeeeeeeeee 8-[8-(8,8-eeeeeeeeeeeeee-8-ee)eeeeeeeeee]-8-eeeeeeeeeeeeeee (88) ee eeeeeeeeeee ee eeeeeeeeeeeee ee eee 8-eeeeeeee eeee eeeeeeeee eeeeeeeee. Meeee eeeeeeeeee eeee 88% ee eee eeeeeee eeeeeeeeee eeeeeeee eeee e eeeee ee M- eee M-eeeeeee (M=M eeee) ee 8:8. Mee eeeeeee eee ee eeeeeeeee ee eeeeeeeeeeee.

Meeeee 88 Meeeeeeee ee 8-Meeeee-8-(eeeeeeeeeeeeee)eeee-8-ee-8-ee[‌888‌]

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Meeeee 88 Meeeeeeee ee Meeeeee-Meeee 8,8-Meeeeeeee-8,8-eeeeee[‌888‌,‌888‌]

Meeeeeeeeeee Meeeeeeee

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eeee-Meeee eeeeeeeeeeeeeeeeeeee (8.88e, 88eeee) eee eeeee ee e eeeeeee eeee ee eeeeee 8-eeeeee-8-eeeeeeeeeeee (8.88e, 88eeee) ee Me8M (888eM). Meeee 8e ee ee, eee eeeeeeeeeee eee eeeeeeeee ee eeeeeeeeee ee eeee eee eeeeeeeee 88 (M=Me; M8=MM8Me; M8=Me; M8=Mee); eeeee: 88.8e (88%); ee 888888°M. Mee. ee MeMMM8 (88eM) eee eeeee ee e eeeeeee ee eee eeeeeeeee 88 (M=Me; M8=MM8Me; M8=Me; M8=Mee; 888ee, 8.88eeee) ee Me8M (88eM). Mee eeeeeeeee eeeeeee eee eeeeeee ee ee eee 8.8e eee eeee eee eeeeeeee eeeee eee eeeeeeeee, eeeeee eeee M8M eee eeeee, eee eeeee (MeMM8). Meeeeee, eee eeeeeee eee eeeeeeeeee ee eeee eee eeeee eeeeeee ee e eee eee; eeeee: 8.88e (88%). Mee ee eee eeeeeeeeeee ee eee eeeeeee ee eee eeee eeeeeeeeeee ee eee eeeeeeeeee eeeeeeee eeee.

8-(Mee-8-ee-8-ee)-8-eeeeeeeeeeeeeeee (88, M8=M; M8=M8=Me; M8=eMe); Meeeeee Meeeeeeee:[‌888‌]

8-Meeeeeeeeee-8-eee (888e, 8.88eee) eee eeeee eeeeeeee ee e eeee ee eeeeeeeeeeeeeeeeee (888e, 8.88eee) ee Me8M (888eM) ee eee eeeeeeee ee MeMM8 (88e) eeee eeeeeeee eeeeeeee, ee eeee e eeee eeee eee eeeeeee eeeeee eeeeeeeeee. Mee eeeeeee eee eeeeeeee eee 8e eee eeee eeeeee ee ee, eee eee-eeee M8M (888eM) eee eeeee. Mee eeeeeee eeeee eee eeeeeeeee, eeeeee eeee M8M, eee eeeee (MeMM8). Meeee eeeeeee ee eee eeeeeee eeeee eeeeeee eeeeeeee, eee eeeeeee eee eeeeeeeee ee e eeeeeeeeeeeee eeeeee ee eeee eee eeeeeee; eeeee: 888e (88%); ee 8888°M/88Meee.

Meeeeeee-8-eeeeeeeeeeee 88; Meeeeee Meeeeeeee:[‌888‌]

MMM (8.8eeeee) eee eeeee eeeeeeeeeee ee ee ee e eeeeeee eeee ee eeeeeeeee 88 (8eeeee) ee MM8Me8 (888eM). Meeeeee eeeeeeeee, eee eeeeeeee α-eeeeeeeeeeeeee 88 eee eeeeeee eeee eee. ee Me8MM8 (8×88eM). Mee eeeeeee eeeee eee eeeee (Me8MM8) eee eee eeeeeee eee eeeeeeeeee eeeee eeeeeee eeeeeeee. Meeeeeeeeeee ee eeeeeeeeeeeeee (eeeeee eee, MeMMe/eeeeeeeeeee) eeeeeeee eee eeeeeeee-8-eeeeeeeeeeee 88; eeeee: 8888%.

References