A direct route to six and seven membered lactones <i>via</i> γ-C(sp<sup>3</sup>)–H activation: a simple protocol to build molecular complexity
作者:Jayabrata Das、Pravas Dolui、Wajid Ali、Jyoti Prasad Biswas、Hediyala B. Chandrashekar、Gaurav Prakash、Debabrata Maiti
DOI:10.1039/d0sc03144e
日期:——
Lactones comprise a class of valuable compounds having biological as well as industrial importance. Development of a methodology to synthesize such molecules directly from readily available materials such as aliphatic carboxylic acid is highly desirable. Herein, we have reported synthesis of δ-lactones and ε-lactones via selective γ-C(sp3)–H activation. The γ-C–H bondcontaining aliphatic carboxylic
We report the ligand‐enabled C−H activation/olefination of freecarboxylicacids in the γ‐position. Through an intramolecular Michael addition, δ‐lactones are obtained as products. Two distinct ligand classes are identified that enable the challenging palladium‐catalyzed activation of freecarboxylicacids in the γ‐position. The developed protocol features a wide range of acid substrates and olefin
palladium‐catalyzed C(sp3)−H activation that enables the directalkynylation of free carboxylic acid substrates. In contrast to previous synthetic methods, no introduction/removal of an exogenous directing group is required. A broad scope of acids including both α‐quaternary and challenging α‐non‐quaternary can be used as substrates. Additionally, the alkynylation in the distal γ‐position is reported. Finally
long-chain ones have been used as substrates in the protocol. A mechanistic investigation has been carried out and suggests C–H activation to be the rate-determining step and a subsequent allylic C–H activation in the reaction. The synthesized lactones having α,β-unsaturated fragments attached are expected to be useful in the synthesis of complex molecules via further synthetic manipulation.
REFRIGERATING MACHINE OIL AND WORKING FLUID COMPOSITION FOR REFRIGERATING MACHINES
申请人:JX Nippon Oil & Energy Corporation
公开号:EP2610329A1
公开(公告)日:2013-07-03
The refrigerating machine oil of the invention includes an ester of a polyhydric alcohol and a fatty acid, wherein the molar ratio of C4-C6 fatty acid and C7-C9 branched fatty acid in the fatty acid is between 15:85 and 90:10, the C4-C6 fatty acid includes 2-methylpropanoic acid, and the ratio of the total C4-C6 fatty acid and C7-C9 branched fatty acid in the total fatty acids composing the ester is at least 20 mol%. The working fluid composition for a refrigerating machine according to the invention comprises the refrigerating machine oil, a difluoromethane refrigerant and/or an unsaturated fluorinated hydrocarbon refrigerant.