Synthesis of Novel Liquid Crystals which Possess gem-Difluorocyclopropane Moieties

Abstract

Synthesis of two types of novel chiral liquid crystal molecules that possess a gem-difluorocyclopropane moiety has been accomplished and their properties of liquid crystal were examined.

Synthesis of optically active gem-difluorocyclopropanes through a chemo-enzymatic reaction strategy

“…These two methods are excellent but are difficult to apply for large-scale preparation, so we developed a synthetic methodology for preparing optically pure gem-difluorocyclopropanes [9,10]. We accomplished the synthesis of trans-1,3-bishydroxymethyl-2,2-difluorocyclopropane (1), cis-(3-hydroxymethyl-2,2-difluorocyclopropyl)methyl acetate (2) and trans,trans -1,6-bishydroxymethyl-2,2,5,5-tetrafluorobicyclopropane (3) and used as the core molecules for synthesizing novel gem-difluorocyclopropane derivatives such as the aminomethyl-substituted cyclopropane 4, 2 oligo-gemdifluorocyclopropanes 5 and 6 [9c,e], and diester 7 which showed a liquid crystal property [10] (Fig. 1).…”

“…1). We describe here the full details of the synthesis of the optically pure mono-and bis-gem-difluorocyclopropanes using lipase-technology [9][10][11][12]. …”

Recent advances in the syntheses, transformations and applications of 1,1-dihalocyclopropanes

“…41 Thus (E,E) 1,6-bis benzyloxyhexa-2,4-diene 72 on treatment with difluorocarbene generated in situ by the pyrolysis of sodium chlorodifluoroacetate afforded the corresponding bis gem-difluorocyclopropane as a mixture of meso 73a and dl pair 73b in equal amounts. 41 Thus (E,E) 1,6-bis benzyloxyhexa-2,4-diene 72 on treatment with difluorocarbene generated in situ by the pyrolysis of sodium chlorodifluoroacetate afforded the corresponding bis gem-difluorocyclopropane as a mixture of meso 73a and dl pair 73b in equal amounts.…”

“…47 Ferroelectric liquid crystalline compounds have wide applications in display appliances. 41 Some of the difluorocyclopropane derivatives show liquid crystalline properties.…”

Synthesis of Novel gem-Difluorinatedcyclopropane Hybrids: Applications for Material and Medicinal Sciences

“…Meijere and co workers reported a unique gem-difluorocyclopropane derivative 17 in optically active form via chemo-enzymatic process and converted it to a novel ferroelectric liquid crystalline compound (77). We also accomplished the synthesis of novel optically active liquid crystal molecules 18 and 19 that possess a gem-difluorocyclopropane moiety (18). It should be noted that compound 19 exhibited an unidentified smectic phase below the SmA phase, while 18 showed only a SmA phase over a wide temperature range.…”