Nonstabilized azomethine ylides as reagents for alkylaminomethylation of aromatic ketones via 5-aryloxazolidines

1,3-Dipolar Cycloaddition Reactions of Azomethine Ylides with Carbonyl Dipolarophiles Yielding Oxazolidine Derivatives

“…The sarcosine/formaldehyde derived azomethine ylide 81 also reacted with (a) aromatic aldehydes bearing an ester group such as 2p, which formed the corresponding oxazolidine 82a, and underwent a subsequent demethylenation/rearrangement process to form (aminomethyl)lactone 93 [90]; and (b) a variety of aromatic ketones 3 to give the 5,5-diaryloxazolidines 94 (Scheme 21, Table 12), which underwent hydrolysis to afford 2-alkylaminoethanols 95 (Scheme 21) [91]. The sarcosine/formaldehyde derived azomethine ylide 81 also reacted with (a) aromatic aldehydes bearing an ester group such as 2p, which formed the corresponding oxazolidine 82a, and underwent a subsequent demethylenation/rearrangement process to form (aminomethyl)lactone 93 [90]; and (b) a variety of aromatic ketones 3 to give the 5,5-diaryloxazolidines 94 (Scheme 21, The same researchers found that an excess of the sarcosine/paraformaldehyde derived azomethine ylide 81 participated in a dual 1,3-dipolar cycloaddition reaction with 3-cyanochromones 96 at both the double bond and the carbonyl group to give diastereoselectively tetrahydro-1H-spiro[chromeno [2,3-c] The same researchers found that an excess of the sarcosine/paraformaldehyde derived azomethine ylide 81 participated in a dual 1,3-dipolar cycloaddition reaction with 3-cyanochromones 96 at both the double bond and the carbonyl group to give diastereoselectively tetrahydro-1H-spiro[chromeno [2,3-c] Azomethine ylides, generated from sarcosine (47) and substituted 2-nitrobenzaldehydes 2, underwent 1,7-electrocylization onto the adjacent nitro group to give unstable benz-1,2,6-oxadiazepines 99. Subsequent ring-contraction afforded mixtures of indazole-N-oxides 100 and 3-methyl-5-aryloxazolidines 82b-e.…”

“…These studies indicate the relatively greater reactivity of such aldehyde and ketone groups over the nitroarene in these particular systems. Using modified conditions (LiF, DMF, reflux), reagent 178 has been employed in azomethine ylide cycloadditions to benzophenone (3c) and acetophenone (3i), to produce good yields of the corresponding oxazolidines 186a and 186b, respectively (Scheme 50) [90]. Acid catalyzed hydrolysis of 186a provided access to 2-amino-1,1-diphenylethylalcohol derivative 187.…”

“…Methyl 2-formyl benzoate (2p) underwent cycloaddition reaction with azomethine ylide 172 generated by trifluoroacetic acid catalyzed decomposition of reagent 178 to give a quantitative yield of oxazolidine 188a which underwent hydrolysis and cyclization under acidic conditions at 70 °C to give phthalide 189a. The less reactive dipolarophile methyl ester of 2-acetylbenzoic acid (3j) gave low yields of the oxazoldine 188b under conditions involving trifluoroacetic acid catalysis; however, with the use of excess LiF in refluxing DMF a 74% yield of Using modified conditions (LiF, DMF, reflux), reagent 178 has been employed in azomethine ylide cycloadditions to benzophenone (3c) and acetophenone (3i), to produce good yields of the corresponding oxazolidines 186a and 186b, respectively (Scheme 50) [90]. Acid catalyzed hydrolysis of 186a provided access to 2-amino-1,1-diphenylethylalcohol derivative 187.…”

Recent Advances in the Synthesis of Hetero- and Carbocyclic Compounds­ and Complexes Based on Acenaphthylene-1,2-dione

“…Moshkin et al 24 reported the reaction of non-stabilized azomethine ylide 58, generated in situ from sarcosine (2), formaldehyde (57), with 1 to give 5-aryloxazolidine 59. Subsequent acid-mediated hydrolysis of the oxazolidine gave aminoalcohol 60 in 47% yield (Scheme 18).…”

Reagents for Storage and Regeneration of Nonstabilized Azomethine Ylides: Spiroanthraceneoxazolidines

“…In previous research, we paid attention to the unusual properties of 3′-methyl-10 H -spiro­[anthracene-9,5′-oxazolidin]-10-one ( 1a ) obtained from anthraquinone, sarcosine, and formaldehyde. Our first attempts to realize any reactions with it, such as hydrolysis to amino alcohol, reduction with NaBH 4 , or even purification by recrystallization from MeOH, resulted in a complicated mixture of products.…”