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Synfacts 2024; 20(03): 0259
DOI: 10.1055/s-0043-1773059
Metals in Synthesis

Regioselective C(sp³)–H Activation of Cyclic Aliphatic Acids: Synthesis of Unsaturated Bicyclic Lactones

Rezensent(en):
Mark Lautens
,
Jonathan Bajohr
Das J, Ali W, Ghosh A, Pal T, Mandal A, Teja C, Dutta S, Pothikumar R, Ge H, *, Zhang X, *, Maiti D. * Texas Tech University, Lubbock, USA; Agency for Science, Technology and Research (A*STAR), Singapore; Indian Institute of Technology Bombay, Mumbai, India
Access to Unsaturated Bicyclic Lactones by Overriding Conventional C(sp3 )–H Site Selectivity.

Nat. Chem. 2023;
15: 1626-1635
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Key words

palladium-catalysis - C–H bond activation - lactones

Significance

Maiti, Zhang, Ge and co-workers report a selective γ-methylene C–H activation in the presence of γ-methyl groups. The subsequent β-H elimination/oxypalladation/β-H elimination cascade furnishes fused unsaturated lactones, which are commonly encountered in natural products. In the presence of an exogenous alkene or allylic alcohol, a quaternary stereocenter can be generated.


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Comment

DFT calculations suggest that although the mono-protected amino acid (MPAA) assisted C–H activation of the methyl C(sp3)–H bond is 3.4 kcal mol–1 lower than that of the methylene group, the subsequent reductive elimination to the corresponding spirocycle has a very high barrier of 45.3 kcal mol–1, making the methylene C(sp3)–H activation pathway more favorable.


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Publikationsverlauf

Artikel online veröffentlicht:
14. Februar 2024

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