Methylamide anion

Acyl imidazolides are more reactive than esters but not as reactive as acyl halides. Entry 7 is an example of formation of a (3-ketoesters by reaction of magnesium enolate monoalkyl malonate ester by an imidazolide. Acyl imidazolides also are used for acylation of ester enolates and nitromethane anion, as illustrated by Entries 8, 9, and 10. (V-Methoxy-lV-methylamides are also useful for acylation of ester enolates. 

Jacobi s synthesis of ( )-paniculide-A involves an intramolecular Diels-Alder reaction of the alkynic ketone (31). This compound was prepared in >90% yield (Scheme 9) by acylation of a lithium alkynide with the A7-methoxy-A7-methylamide (30). Addition of the anion to other derivatives related to (30) such as an acid chloride, a trifluoroacetic mixed anhydride, an acyl imidazole, S-(2-pyridyl) thiolates and a mixed carbonic anhydride (from ethyl chloroformate) led to either bis-addition or to proton abstraction. Notice should be made of the stability exhibited by the A7-methoxy-A7-methylamide group while the oxa-zole moiety was being introduced. ... 

Thermolysis of the sulfone 58 gave 58% of a mixture of geraniol (25) and nerol (27) ethyl ethers. Starting from senecioic acid (59), Katzenellenbogen has continued studies of the addition of prenyl halides (15, R = halogen) to the dianion in presence of copper. Copper ion also influenced the addition of prenyl bromide (15, R = Br) to the anion of the V-methylamide of 59, its presence transforming a yield of 98% of the a-addition product to 83% of the y-product, geranic acid V-methylamide [as a mixture of (Z)- and ( )-isomers]. ... 

When multiple labelling in any of the primed or unprimed positions 8, 9, 12, 13, 19 and 20 is required, the route is slightly modified (Scheme 5). First the ketone is coupled with the anion of triethyl phosphonoacetate (11), as described above (Scheme 3). The ester product 12 is converted into the A -methoxy-A -methylamide (16) by reacting it with the anion prepared by deprotonation of A, 0-dimethylhydroxylamine with BuLi. The amide 16 can now be reacted with methyl magnesium iodide (17) as described above, thus giving access to carotenoids with multiple labelling in the required positions via the multiply labelled ketone 7 [38]. 

This pathway is also used in the synthesis of modified carotenoids with extra side-chain methyl groups whilst the amide phosphonate 15 is reactive enough to couple to aldehydes, its reactivity is not sufficient for it to couple to ketones in high yield. Therefore, the anion of triethyl phosphonoacetate (11) is first coupled to the ketone, and the ester group of the product is converted into the amide, giving the A -methoxy-A -methylamide 16 [38]. 

Conversion of the iV-methylamide of linoleic acid into a mixture of conjugated 9,11- and 10,12-iV-methyloctadecadienamides (cisjrans- after short reaction, trans,trans- after prolonged treatment), and reduction of aj8-unsaturated ketones and lactones to their radical anions (ketyls), are brought about by an alkali-metal methylsulphinylmethylide. 

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