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Mechanistic Investigations of the Pd‐Catalyzed Hydrogenolysis of Ketene Heterodimer β‐Lactones
Author(s) -
Panda Manashi,
Mondal Mukulesh,
Chen Shi,
Ibrahim Ahmad A.,
Twardy Dylan J.,
Kerrigan Nessan J.
Publication year - 2020
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/ejoc.202000976
Subject(s) - chemistry , ketene , hydrogenolysis , substituent , aryl , stereochemistry , lactone , olefin fiber , chirality (physics) , medicinal chemistry , catalysis , axial chirality , derivative (finance) , enantioselective synthesis , organic chemistry , alkyl , nambu–jona lasinio model , chiral symmetry breaking , physics , quantum mechanics , financial economics , economics , quark
Catalytic hydrogenolysis of the Z ‐isomer of a series of aryl‐substituted ketene heterodimer β‐lactones facilitated access to deoxypropionate derivatives with a dr ranging from 54:46 to 86:14, favoring the anti ‐isomer, and with excellent transfer of chirality (91 → 99 % ee for 13 examples). Although X = 4‐F was determined to provide optimal diastereoselectivity ( dr 86:14), a non‐linear relationship between diastereoselectivity and aryl substituent σ values was found. For cases where a para ‐ or ortho ‐EWG was present on the aryl ring of the ketene heterodimer, formation of significant amounts of β‐lactone (20–44 %) as by‐product was observed. The results of a number of control reactions point to anti ‐β‐elimination and an anti ‐selective hydrogenation of an E ‐isomer olefin intermediate being key steps in the reaction mechanism. The synthetic potential of the deoxypropionate derivative products was demonstrated by oxidative conversion into a 1,5‐difunctionalized deoxypropionate motif.