Cyclocondensation of amidines with dimethyl acetylenedicarboxylate: A convenient entry into tetramic acids

Abstract

Amidines undergo cyclocondensations with dimethyl acetylenedicarboxylate (DMAD) to give highly functionalized 5‐dialkylamino‐4‐pyrrolin‐3‐ones. The products are crystalline, highly colored compounds that are uniquely functionalized and represent advanced intermediates in the construction of several other heterocyles, in particular the biologically active tetramic acids. The synthetic transformations of these compounds to tetramic acids are also described.

Reaction of cyclic imidates with α,β‐unsaturated esters: Synthesis of new pyrrolo[2,1‐b]‐1,3‐oxazine and pyrido[2,1‐b]‐1,3‐oxazine derivatives

“…The compounds, 3a , 3b , 3c , 3d , 3e , 3f , were characterized by 1 H NMR, 13 C NMR, MALDI‐TOF‐MS spectral, and elemental analysis data. E ‐Forms of 3a , 3b , 3c , 3d , 3e , 3f were identified by the characteristic signals for the olefinic hydrogen atoms on the acetate moieties at δ 6.15–6.19 in 1 H NMR spectrum [4]. In addition, the compounds, 5a‐f, were analyzed by means of HMBC in NMR technique.…”

Five‐Membered Heterocycles: Pyrrole and Related Systems

“…The Dieckmann cyclization strategy has also been utilized in a solid phase approach starting from amino acid derivatives attached to the resin by an ester linkage [632]. A recent contribution to this field encompasses preparation of 5-substituted teramic acid derivatives by cyclocondensation of amidines with DMAD, followed by alkaline hydrolysis of the intermediate 5-amino-4-pyrrolin-3-ones [633].…”

Recent development in the synthesis of pyrrolin‐4‐ones/pyrrolin‐3‐ones

“…The DMAD-amidine cyclo-condensations proceed readily at low temperatures to afford 5-dialkyl (or alkylaryl)amino-4-pyrrolin-3-ones 48 as highly colored crystalline compounds in moderate to good yields (Scheme 12). 14 Palacios et al described a versatile synthetic methodology for the synthesis of 5-amino-pyrrolidin-3-ones 56 The reactions of 2-azadienes 50a (R 1 = R 3 = Me, R 2 = CO 2 Me) with diethyl azodicarboxylate 51 afford the acyclic derivative 53. On heating acyclic compound 53 in refluxing, toluene affords 52 in (6%) and 56 (56%).…”

“…The DMAD‐amidine cyclo‐condensations proceed readily at low temperatures to afford 5‐dialkyl (or alkylaryl)amino‐4‐pyrrolin‐3‐ones 48 as highly colored crystalline compounds in moderate to good yields (Scheme 12). 14 …”