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34.1.6.4.2 Substitution of Carboxy or Alkoxycarbonyl Groups

DOI: 10.1055/sos-SD-134-00125

Yamazaki, T.Science of Synthesis Knowledge Updates, (20172288.

Decarboxylative allylation occurs in the presence of the tris(dibenzylideneacetone)dipalladium(0) complex and the chiral ligand (S)-2-{2-(diphenylphosphino)phenyl}-4-tert-butyl-4,5-dihydrooxazole [(S)-t-Bu-PHOX, 21] if β-keto ester 22[‌16‌‌18‌] or its regioisomeric enol carbonate 25 is employed as the substrate to give 2-allyl-2-fluorodihydronaphthalen-1-one 23 (Scheme 11).[‌19‌] In addition, analogues of 25, such as enol silyl ether 24,[‌20‌] lead to the construction of the identical product 23 in excellent yields with excellent enantiomeric purities. A very interesting feature of these processes is that successful results, especially in terms of the enantiomeric selectivity and the chemical yield, are highly dependent on the molar ratio between ligand 21 and the palladium catalyst. For example, 23 is obtained in 94% yield with 93% ee by transformation of 22 using a ligand 21/palladium ratio of 1.25:1, but it is obtained in only 50% yield with 89% ee using a 1:4 ratio of ligand 21/palladium.

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(M)-8-Meeee-8-eeeeee-8,8-eeeeeeeeeeeeeeeee-8(8M)-eee (88); Meeeeee Meeeeeeee eee eee Meeeeeeeeeeeeeee Meeeeeeeeeeeeee Meeeeeeeee ee β-Meee Meeee 88:[‌88‌]

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(M)-8-Meeee-8-eeeeee-8,8-eeeeeeeeeeeeeeeee-8(8M)-eee (88); Meeeeee Meeeeeeee eee eee Meeeeeeeeeeeeeee Meeeeeeeee ee Meee Meeee Meeee 88:[‌88‌]

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References


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