476429-07-9Relevant articles and documents
Cu(I)/chiral bisoxazoline-catalyzed enantioselective sommelet-hauser rearrangement of sulfonium ylides
Wang, Jianbo,Li, Shu-Sen
supporting information, p. 12343 - 12358 (2020/11/10)
Catalytic asymmetric thia-Sommelet-Hauser rearrangement of sulfonium ylides remains a great challenge due to its multistep reaction mechanism involving metal carbene formation, proton transfer, and [2,3]-sigmatropic rearrangement. In particular, the key problem of such reactions is the differentiation of the enantiotopic lone pair electrons of sulfur, which generates the sulfonium ylide intermediate bearing chirality on the sulfur atom. With a modified chiral bisoxazoline ligand, we developed a Cu(I)- catalyzed asymmetric thia-Sommelet-Hauser rearrangement with good to excellent enantioselectivities. Mechanistic studies provide insights into the details of the reaction mechanism.
Efficient synthesis of α-aryl esters by room-temperature palladium-catalyzed coupling of aryl halides with ester enolates
Jorgensen, Morten,Lee, Sunwoo,Liu, Xiaoxiang,Wolkowski, Joanna P.,Hartwig, John F.
, p. 12557 - 12565 (2007/10/03)
A catalytic amount of Pd(dba)2 ligated by either carbene precursor N,N′-bis(2,6-diisopropylphenyl)-4,5-dihydroimidazolium (1) or P(t-Bu)3 mediated the coupling of aryl halides and ester enolates to produce α-aryl esters in high yields at room temperature. The reaction was highly tolerant of functionalities and substitution patterns on the aryl halide. Improved protocols for the selective monoarylation of tert-butyl acetate and the efficient arylation of α,α-disubstituted esters were developed with LiNCy2 as base and P(t-Bu)3 as ligand. In addition, tert-butyl esters, such as those of Naproxen and Flurbiprofen, were prepared from tert-butyl propionate and aryl bromides in high yields in the presence of Pd(dba)2 and the hindered, saturated heterocyclic carbene ligand precursor.
