Chiral linear polymers bonded alternatively with salen and 1,4-dialkoxy-2,6-diethynylbenzene: synthesis and application to diethylzinc addition to aldehydes

The synthesis of chiral polymers 1 bonded alternatively with salen and 1,4-dialkoxy-2,6-diethynylbenzene was accomplished. These polymers are recyclable and catalyze the Et2Zn addition to aldehydes with good enantioselectivity.

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(S)-(−)-1-Phenyl-1-propanolC9H12OEe = 50%[α]D25=-13 (c 1, CHCl3)Source of chirality: asymmetric Et2Zn additionAbsolute configuration: (S)

(S)-(−)-1-(3-Nitrophenyl)-propan-1-olC9H12NO3Ee = 70%[α]D25=-23 (c 1.2, EtOH)Source of chirality: asymmetric Et2Zn additionAbsolute configuration: (S)

(S)-(−)-1-(4-Methoxyphenyl)-1-propanolC10H14O2Ee = 60%[α]D25=-22 (c 1.1, benzene)Source of chirality: asymmetric Et2Zn additionAbsolute configuration: (S)

Chiral linear polymer bonded alternatively with salen and 1,4-dialkoxy-2,6-diethynylbenzeneR = C8H17O[α]D25=+376 (c 0.1, THF)Source of chirality: (1R,2R)-diaminocyclohexaneAbsolute configuration: (R,R)

Chiral linear polymer bonded alternatively with salen and 1,4-dialkoxy-2,6-diethynylbenzeneR = C8H17O[α]D25=+166 (c 0.1, CHCl3)Source of chirality: (1R,2R)-diphenylethylenediamineAbsolute configuration: (R,R)