Microwave‐Assisted Convenient Synthesis of α,β‐Unsaturated Esters and Ketones via Aldol‐Adduct Elimination

Abstract

Various fluorinated 3‐oxo ester/1,3‐diketones were reacted with carbonyl compounds, in presence of piperidine and under microwave irradiation, to afford (E)‐α,β‐unsaturated esters and ketones in good yields. The systematic study reveals that the reaction proceeded through the formation of aldol adduct. The method provides a new and simple way for C,C bond formations.

Efficient Synthesis of α,β‐Unsaturated Ketones from Primary Alcohols and Ketones over Mg2+‐Modified NiGa Hydrotalcites

“…For the aldol condensation step, activation of nucleophile is important, and alcohol firstly formed after the nucleophilic attack. It was reported that piperidine as a base in the reaction system is necessary to promote the following elimination reaction ,. Surface basic sites of LDH might play the similar role to accelerate the reaction in the present system.…”

A Novel Approach for C–C, C–N, and C–O Bond Formation Reactions: A Facile Synthesis of Benzophenazine, Quinoxaline, and Phenoxazine Derivatives via Ring Opening of Benzoxepines

“…Our research focused on the synthesis of biologically active heterocyclic compounds, and feasible reactions of carbonyl compounds/salicylaldehydes with 3-oxobutanoates bearing chloro or trifluoro substituents. In this context, we studied the reactivity of carbonyl compounds with ethyl 4,4,4-trifluoro-3-oxo­butanoate using piperidine in CH 2 Cl 2 at room temperature to provide a series of ( E )-α,β-unsaturated esters and ketones . Next, we studied the reactivity of various salicylaldehydes with ethyl 4-chloro-3-oxobutanoate using piperidine to provide 2 H -chromenes, interim these derivatives were successfully converted to corresponding 2,3-dihydro­benzoxepine-4-carboxylates .…”