A Simple and Convenient Synthesis of 4‐Ylidene‐5(4H)oxazolone Derivatives: Oxazolone Ring Transformation Leading to Other Heterocyclic Structures

Abstract

in Wiley Online Library (wileyonlinelibrary.com).Simple, effective, and high yield synthetic procedure for the synthesis of 4-ylidene-5(4H)-oxazolones 2a-m from arylidene-malononitriles under solvent-free conditions is described. The scope of this reaction was investigated, and it was found that the presence of anhydrous sodium acetate gave the corresponding oxazolones in excellent yields. The newly generated oxazolone derivative 2m underwent ring transformation into pyrroles, imidazoles, pyridazine, and triazines.

An eco-compatible access to diversified bisoxazolone and bisimidazole derivatives

“…As a continuation of our work towards developing novel protocols for the synthesis of oxazolones 18 and bisheterocycles from dialdehydes, 30,34 we have progressed with respect to the design and preparation of the bisoxazolones (2a-f). In this context, reactive precursors such as dialdehyde derivatives (1a-f) can react effectively with hippuric acid (HA) and acetic anhydride (Ac2O).…”

“…16,17 Our group developed a new strategy for the assembly of arylideneoxazolones starting from arylidenemalononitriles using solvent-free conditions. 18 Although several structural analogs have been prepared, a careful literature survey showed that only one synthetic method has been used for the construction of bisoxazolones. 19 Hence, the development of more convenient and ecofriendly strategies for the preparation of oxazolones and bisoxazolones would be advantageous.…”

Bulky Dehydroamino Acids Enhance Proteolytic Stability and Folding in β-Hairpin Peptides

“…Saponification was followed by a one-pot dehydration-cyclization sequence mediated by NaOAc and Ac 2 O. 25 We originally employed Ac 2 O as solvent, 23 but challenges in completely removing this high-boiling compound from 5 prior to the ring-opening reaction led us to devise a new procedure utilizing THF as solvent. The yields listed in Table 1 for azlactones 6 were affected by partial decomposition during SiO 2 chromatography.…”

“…In contrast to our prior work, the use of rigorously purified samples of 4b enabled EDC·HCl and HOBt to be employed in couplings instead of the more expensive COMU. Saponification was followed by a one-pot dehydration–cyclization sequence mediated by NaOAc and Ac 2 O . We originally employed Ac 2 O as solvent, but challenges in completely removing this high-boiling compound from 5 prior to the ring-opening reaction led us to devise a new procedure utilizing THF as solvent.…”