Synthesis of two new chiral fluorous bis(oxazolines) and their applications as ligands in catalytic asymmetric reactions

Two new chiral fluorous bis(oxazolines) with a fluorous content of 56.9% and 59.3%, respectively, have been prepared starting from (S)-serine and (S)-tyrosine. Applications of these compounds as fluorous box ligands in asymmetric alkylations gave ees up to 92%, and in allylic oxidations ees up to 50%. Recycling and reuse of the ligands in asymmetric alkylation and of the catalytic system in allylic oxidation gave the same enantioselectivities.

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(S)-O-Allyl-N-Boc-serine methyl esterC12H21NO5Ee = 100%[α]D25=+16.9 (c 0.4, CHCl3)Source of chirality:(S)-serineAbsolute configuration:(S)

(S)-N-Boc-O-(1H,1H,2H,2H,3H,3H-perfluoroundecanyl)serine methyl esterC20H22F17NO5Ee = 100%[α]D25=+10.9 (c 0.6, CHCl3)Source of chirality:(S)-serineAbsolute configuration:(S)

(S)-O-(1H,1H,2H,2H,3H,3H-Perfluoroundecanyl)serine methyl esterC15H14F17NO3Ee = 100%[α]D25=+1.8 (c 0.4, CHCl3)Source of chirality:(S)-serineAbsolute configuration:(S)

(R)-2-Amino-3-[(1H,1H,2H,2H,3H,3H-perfluoroundecanyl)oxy]propan-2-olC14H14F17NO2Ee = 100%[α]D25=+0.6 (c 0.5, CHCl3)Source of chirality:(S)-serineAbsolute configuration:(R)

(4S,4′S)-2,2′-Methylene-bis[4-{(1H,1H,2H,2H,3H,3H-perfluoroundecanyl)oxy}methyl]-4,5-dihydro-1,3-oxazoleC31H24F34N2O4Ee = 100%[α]D25=-8.3 (c 0.2, CHCl3)Source of chirality:(S)-serineAbsolute configuration:(4S,4′S)

(S)-O-Allyl-N-Boc-tyrosine methyl esterC18H25NO5Ee = 100%[α]D25=+48.8 (c 1, CHCl3)Source of chirality:(S)-tyrosineAbsolute configuration:(S)

(S)-O-Allyl-tyrosine methyl esterC13H17NO3Ee = 100%[α]D25=+10 (c 1, CHCl3)Source of chirality: (S)-tyrosineAbsolute configuration: (S)

(R)-3-[4-Allyloxyphenyl]-2-aminopropanolC12H17NO2Ee = 100%[α]D25=-14.5 (c 1, CHCl3)Source of chirality: (S)-tyrosineAbsolute configuration: (R)

(4S,4′S)-2,2′-Methylenebis[4-(4-allyloxybenzyl)-4,5-dihydro-1,3-oxazole]C27H30N2O4Ee = 100%[α]D25=-16.9 (c 1, CHCl3)Source of chirality: (S)-tyrosineAbsolute configuration: (4S,4′S)

(4S,4′S)-2,2′-(1H,1H,2H,2H,3H,3H-Perfluorotricosane-12,12-diyl)bis[4-(4-allyloxybenzyl)-4,5-dihydro-1,3-oxazole]C49H40F34N2O4Ee = 100%[α]D25=-9.7 (c 1, CHCl3)Source of chirality: (S)-tyrosineAbsolute configuration: (4S,4′S)

(4S,4′S)-2,2′-(1H,1H,2H,2H,3H,3H-Perfluorotricosane-12,12-diyl)bis-[4-(4-hydroxybenzyl)-4,5-dihydro-1,3-oxazole]C43H32F34N2O4Ee = 100%[α]D25=-19.3 (c 1, acetone)Source of chirality: (S)-tyrosineAbsolute configuration: (4S,4′S)

(4S,4′S)-2,2′-(1H,1H,2H,2H,3H,3H-Perfluorotricosane-12,12-diyl)bis-[4-(4-(1H,1H-perfluoroctyloxybenzyl))-4,5-dihydro-1,3-oxazole]C59H34F64N2O4Ee = 100%[α]D25=+21.6 (c 0.5, C6H5CF3)Source of chirality: (S)-tyrosineAbsolute configuration: (4S,4′S)