Synthesis of Amides From Esters and Amines Under Microwave Irradiation

Mild and Efficient DBU-Catalyzed Amidation of Cyanoacetates

“…The use of potassium tert -butoxide ( t -BuOK) for the synthesis of cyanoacetamides under microwave conditions is known (see ref ); however, it led to low conversions in our case at 23 °C in 1-BuOH.…”

“…One of the most efficient and atom-economical options for the formation of an amide is the reaction of an amine with a simple ester. Alkyl cyanoacetates have been converted to simple cyanoacetamides in moderate to high yield under solvent-free conditions, , with microwave irradiation, or at high temperatures. , Amidation has also been accomplished using lithium amides derived from primary and secondary amines at low temperatures . However, none of these protocols seemed attractive for the large-scale manufacture of 1 .…”

Facile and Divergent Synthesis of Lamellarins and Lactam‐Containing Derivatives with Improved Drug Likeness and Biological Activities

“…Following our established methodology, [9] benzyldihydroisoquinoline derivatives were successfully synthesized from arylacetic acid 8 or 9 anda ryl ethylamine 10,b otho fw hich were generated by using appropriately substituted benzaldehyde derivatives as the buildingb locks (see the Experimental Section for details). For 2-bromo-a-nitrocinnamate (11), on the other hand, the conditions previously used to prepare 2-bromo-O-benzylvanillin (13)g ave relativelyl ow yield (25-45%)a nd,t hus, were optimized in this study.…”

“…Given that our attempts at tandeml actamization were unsuccessful, at wo-stepa pproach was employed by first converting pyrrole ester 6 into corresponding pyrrole amide 19 without an N-protecting group, if possible, to avoid the complications generally experienced during its removal.T hus,m odel studies were initially undertaken for direct amidation of methyl benzoate (see the Supporting Information for details). As shown in Scheme 5, the unique combination of either sodium amide or trimethylsilyl (TMS) azide as the nitrogen nucleophile and trimethylaluminum as the Lewis acid [11] unexpectedly gave product 26 in good yield (80-89 %). In contrast, the reactions performed witht he use of other nitrogen sources (NaN 3 ,N H 4 Cl, or NH 2 OH·HCl) under different conditions (tetrahydrofuran (THF), 1,4-dioxane, or toluene as solvent at 60-200 8Cw ith 100-300 Wo fM Wp ower for 30-45min) either did not proceed or gave lower yields of the corresponding products.…”

Nonthermal Effects of Microwaves in Organic Synthesis

“…In a parallel study [196], it was shown that formamide and primary and secondary amines react with esters in the presence of potassium tert-butoxide under MW irradiation. Substituted amides are formed in yields much higher (generally more than 70%) than under the action of conventional heating (Scheme 4.19, Table 4 …”