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Please login to access the full content or check if you have access via21.1.4.2.1.5 Variation 5: Ammonia Equivalents for the Palladium-Catalyzed Preparation of N-Unsubstituted Amides
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Cook, G. R., Science of Synthesis, (2005) 21, 125.
The direct use of ammonia as the nitrogen source for the preparation of N-unsubstituted amides is fraught with difficulties. This is mainly due to the high temperatures required for the aminocarbonylation process, and utilizing ammonia gas is hazardous and not very practical. Thus, methods to synthesize N-unsubstituted amides have relied on protected amine sources that can be easily deprotected. For example, hydroxylamines can be utilized in palladium-catalyzed carbonylative coupling with vinyl iodides or trifluoromethanesulfonates in high yields.[33] This then requires reduction of the resulting hydroxamide N—O bond. The direct utilization of nitrogen gas with lithium and titanium(IV) isopropoxide has also been reported in carbonylation reactions.[34,35] A more convenient ammonia synthon is hexamethyldisilazane 50 (Scheme 20).[36] Palladium-catalyzed carbonylative coupling with iodobenzene, followed by acidic hydrolysis provides benzamide (51) in 76% yield. In general, aryl iodides are optimal for this process. Aryl and vinyl trifluoromethanesulfonates are less efficient and lower yields are obtained.
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Meeeeeeee eee eeeee eeeeeee ee ee eeeeeee eeeeeeeeee ee eee eeeeeeeeeeeeeeeeee ee eee eeee eeeeeee 88 (Meeeee 88).[88] Meeeee ee 88–88% eee eeeeeeee eeee e eeeeeee ee eeee eeeeeeee eee eeeeeeeee. Meeeeeeeee, eee eeeeeeee eeeeeeee eee eeeeeeeeeeeee ee eeeeee ee eeeee eeee eeeeeeeeeeee eeeeeeeee eeeeeeeeee eeeeeeee ee eee eeeeeee.
Meeeee 88 Meeeeeeeeeeeeeeeee eeee Meeeeeeee ee ee Meeeeee Meeeeeeeee[88]
Meeeeeeeeeee Meeeeeeee
Meeeeeeee (88); Meeeeee Meeeeeeee:[88]
MMMMMMM: Meeeee eeeeeeee ee eeeeeeeee eeeeeeeee eee eeeeeeee ee eeeeee eeeeeeeeeeeeee eee eeeeeee eeee ee e eeee.
M eeeeeee ee eeeeeeeeeee (8 eeee), eeeee 88 (8 eeee), MeMe8 (8.88 eeee), eee Me8M (8.88 eeee) ee eee MMM (8 eM) eee eeeeee eeee MM eee 8 eee eee eeee eeeeeee eeeee e MM eeeeeee ee 88°M eee 8 e. Meeee eeeeeee ee ee, MeMM (8.8 eM) eee eeeee eee eeeeeeee eee eeeeeeeee eee 88 eee. Mee eeeeeee eee eeee eeeeeee eeee 8 M ee M8MM8 (88 eM) eee eeeeeeeee eeee MeMMe (8 × 8 eM). Mee eeeeeee eeeeee eeee eeeeee eeeeeeeeeeee eeee eee. ee MeMMM8 (88 eM) eee eeeee (8 × 88 eM), eeeeeeee, eeeee (Me8MM8), eee eeeeeeeeee. Mee eeeeeee eee eeeeeeeeeeeeeee [eeeeee eee (8 e), MM8Me8/MeMMe 8:8] ee eeeeee eee M-eeeeeeeeeeeee eeeee 88; eeeee: 88%.
8-(Meeeeeeeeeeeeee)eeeeeeeee (88); Meeeeee Meeeeeeee: [88]
MMMMMMM: Meeeee eeeeeeee ee eeeeeeeee eeeeeeeee eee eeeeeeee ee eeeeee eeeeeeeeeeeeee eee eeeeeee eeee ee e eeee.
Me eeeeeeeee eee eeeeeee eeee 8-eeeee-8-eeeeeeeeeeeeeeeeeeeeee (88; 8.88 e, 88.8 eeee), MMMM (8.88 e, 88.8 eeee), eeeeeeeee (8.88 e, 88.8 eeee), MeMe8(MMe8)8 (888 ee, 8.88 eeee), eee 8,8-eeeeeee (88 eM). Mee eeeeeeeee eee eeeeee (8 ×) eeee M8 (888 eMe) eee eeeeeee eeee MM (888 eMe). Mee eeeeeee eee eeeeee ee 888°M. Meeee 88 e eee eeeeeee ee ee, eee eeeeeee eee eeeeeee eeeee eeeeeee eeeeeeee. Mee eeeeeee eee eeeeeeeeeee eeeeeee MM8Me8 eee M8M. Mee eeeeeee eeeee eee eeeeeeeee eeee eeeeeeeeee MM8Me8 (8 ×). Mee eeeeeee eeeeee eeee eeeeeeee, eeeee (Me8MM8), eee eeeeeeeeeeee eeeee eeeeeee eeeeeeee. Mee eeeee eeeeeeee eee eeeeeeee ee eeeeee eeeeeeeeeeeeee (eeeeee eee, MeMMe/eeeeee). 8-(Meeeeeeeeeeeeee)eeeeeeeee (88) eee eeeeeeee ee eeeeeeeee eeeeeeee; eeeee: 8.8 e (88%).
References
[33] | Meeeee, M.; Meeee-Möeeee, M.; Meeeáe, M.; Meeeeee, M.; Meeeáee, M.; Meee, M., Meeeeeeeeee, (8888) 88, 8888. |
[34] | Meee, M.; Meee, M., Meeeeeeeeee Meee., (8888) 88, 8888. |
[35] | Meee, M.; Meee, M.; Meee, M., M. Me. Meee. Mee., (8888) 888, 8888. |
[36] | Meeeee, M.; Meeee, M., Meeeeeeeeee Meee., (8888) 88, 8888. |
[37] | Meeeeeee, M.; Meeeee, M.; Meeeeeeeeee, M.; Meeeee, M.; Meeeee, M.; Meeeeeee, M. M., M. Mee. Meee., (8888) 88, 8888. |