Organic acid induced olefination reaction of lactones

Abstract

(Z)-Selective olefination of several lactones with ketene silyl acetals was achieved by the catalysis of carbon acids (C-H acids) having a bis(triflyl)methyl group as an acidic functionality; in particular, the triple carbon acid having three bis(triflyl)methyl groups in phloroglucinol shows an excellent catalytic performance.

Ternary PtPdCu Electrocatalyst Formed through Surface‐Atomic Redistribution against Leaching

“…(2); TBS= tert ‐butyldimethylsilyl]. Furthermore, the present zwitterion catalysis was applied to the olefination reaction of lactone substrates, which was recently developed by our group 6a. The reaction of isochroman‐1‐one required the use of at least 2 mol % of 3 c (with three acidic carbon centers) for the complete consumption of starting lactone 13.…”

Organic Acid Catalysts in Reactions of Lactones with Silicon Enolates

“…Furthermore, we have recently reported that, in the presence of multiple carbon acids bearing more than two or three Tf 2 CH groups in the molecular structure, the reaction of lactone substrates with KSAs proceeds smoothly to give unusual olefination products without the ring-opening of the lactone functionality. [11] Herein, we describe the full details of our work in relation to organic-acid catalysis in the reactions of lactones with KSAs. In the presence of the multiple carbon acid catalyst, the reaction of a wide range of arene-fused lactones smoothly gave the corresponding (Z)-vinyl ethers in good to excellent yields.…”

Synthesis of δ-Oxo-1,1-bis(triflyl)alkanes and Their Acidities

“…The p K a of 1 in DMSO is also measured as 2.1 and it works as a better proton donor relative to trifluoroacetic acid (p K a in DMSO = 3.45). On the basis of this feature, some powerful Brønsted acid catalysts containing Tf 2 CH functionalities such as Tf 2 CHC 6 F 5 [4,5,6], Tf 2 CHCH 2 CHTf 2 [7,8,9,10], and multiple carbon acids [11,12,13] were developed. Compared to the corresponding nitrogen acid Tf 2 NH and oxygen acid TfOH, these carbon acids show excellent catalyst performance in several synthetic reactions, including the Mukaiyama aldol reaction, the Friedel–Crafts acylation, and esterification.…”