Synthesis of several polyethers derived from BINOL and their application in the asymmetric borane reduction of prochiral ketones

Several novel epoxy monomers, (S,S)- or (S,R)-3-(glycidyloxy)methyl-2,2′-bis(methoxymethyloxy)-1,1′-binaphthalene and (S,S)- or (S,R)-6-(glycidyloxy)methyl-2,2′-bis(methoxymethyloxy)-1,1′-binaphthalene, which were derived from chiral BINOL and epichlorohydrin, were synthesized and underwent anionic polymerization and deprotection of the MOM groups to obtain soluble polyethers. These polyethers were used to induce the enantioselective borane reduction of prochiral ketones. The substrates gave up to 98% yield with over 99% ee values. The recovered polyethers could be reused many times to induce the enantioselective reduction of prochiral ketones without losing their enantioselective induction ability.

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(S)-3-Hydroxymethyl-2,2′-bis(methoxymethyloxy)-1,1′-binaphthaleneC25H24O5[α]D20 = −65.8 (c 0.05, THF)Source of chirality: (S)-BINOLAbsolute configuration: (S)

(S,S)-3-(Glycidyloxy)methyl-2,2′-bis(methoxymethyloxy)-1,1′-binaphthaleneC28H28O6[α]36520 = −502.8 (c 0.1, THF)Source of chirality: (S)-BINOL and (S)-epichlorohydrinAbsolute configuration: (S,S)

(S,R)-3-(Glycidyloxy)methyl-2,2′-bis(methoxymethyloxy)-1,1′-binaphthaleneC28H28O6[α]36520 = −471.0 (c 0.1, THF)Source of chirality: (S)-BINOL and (R)-epichlorohydrinAbsolute configuration: (S,R)

(S)-6-Hydroxymethyl-2,2′-bis(methoxymethyloxy)-1,1′-binaphthaleneC25H24O5[α]D20 = −58.2 (c 0.05, THF)Source of chirality: (S)-BINOLAbsolute configuration: (S)

(S,S)-6-(Glycidyloxy)methyl-2,2′-bis(methoxymethyloxy)-1,1′-binaphthaleneC28H28O6[α]36520 = −154.5 (c 0.1, THF)Source of chirality: (S)-BINOL and (S)-epichlorohydrinAbsolute configuration: (S,S)

(S,R)-6-(Glycidyloxy)methyl-2,2′-bis(methoxymethyloxy)-1,1′-binaphthaleneC28H28O6[α]36520 = −102.4 (c 0.1, THF)Source of chirality: (S)-BINOL and (R)-epichlorohydrinAbsolute configuration: (S,R)