Axially chiral phosphine–oxazoline ligands in the silver(I)-catalyzed asymmetric Mannich reaction of fluorinated aldimines with trimethylsiloxyfuran

Axially chiral phosphine–oxazoline ligand L7, prepared from (S)-binol, was found to be a fairly effective chiral ligand in the silver(I)-catalyzed asymmetric Mannich reaction of fluorinated aldimines with trimethylsiloxyfuran to give the corresponding adducts in up to 99% yield, over 20:1 dr and 81% ee.

Figure optionsDownload as PowerPoint slide

(S)-4-tert-Butyl-(2)-((S)-2′-(diphenylphosphino)-1,1′-binaphthyl-2-yl)-4,5-dihydrooxazoleC39H34NOPEe = 100%[α]D20=-112.2 (c 1.0, CH2Cl2)Source of chirality: resolution and chiral poolAbsolute configuration: (aS,S)

(S)-4-tert-Butyl-2-(1-((S)-2-(diphenylphosphino)naphthalen-1-yl)-3-(trimethylsilyl)naphthalen-2-yl)-4,5-dihydrooxazoleC38H33NOPSiEe = 100%[α]D20=-83.6 (c 1.0, CH2Cl2)Source of chirality: resolution and chiral poolAbsolute configuration: (aS,S)

Ethyl 3-((S)-4-tert-butyl-4,5-dihydrooxazol-2-yl)-4-((S)-2-(diphenylphosphino) naphthalene-1-yl)-2-naphthoateC38H29NO3PEe = 100%[α]D20=-142.5 (c 0.36, CH2Cl2)Source of chirality: resolution and chiral poolAbsolute configuration: (aS,S)