A correlation of optical rotation, optical purity and configuration of the asymmetric center was done for 2-0-methoxyethoxymethylglycerol bearing polyunsaturated fatty acyl group at sn-1 position. This compound was enzymatically prepared and is an important starting material for the syntheses of optical active glycerophospholipids naving polyunwaturated fatty acyl groups.自然界に広く存在し，重要な生理機能を担っている多価不飽和脂肪酸結合リン脂質の化学的合成に必要な出発原料としての2-0-methoxyethoxymethylglycerolの立体配置と光学純度を，立体配置・光学純度既知の物質に化学的に誘導し，それらの比旋光度をお互いに比較する事により決定した

Baba, Naomichi

Matsumoto, Kotaro

Mori, Yoshihiro

Nakajima, Shuhei

Shimizu, Sakayu

Okayama University Scientific Achievement Repository

StereochemicalDeterminationof2-O-MethoxyethoxymethylglycerolBearingPolyunsaturatedFattyAcylGroupatsn-1PositionKotaroMatsumoto,YoshihiroMori??,ShuheiNakajimaNaomichiBabaandSakayuShimizu??(DepartmentofBioresourcesChemistry)Acorrelationofopticalrotation,opticalpurityandconfigurationoftheasym-metriccenterwasdonefor2-O-methoxyethoxymethylglycerolbearingpolyunsatur-atedfattyacylgroupatsn-1position.Thiscompoundwasenzymaticalypreparedandisanimportantstartingmaterialforthesynthesesofopticalyactiveglycero-phospholipidshavingpolyunsaturatedfattyacylgroups.Keywords:phospholipid,polyunsaturatedfatyacid,methoxyethoxymethylglycerol,synthesisInrecentyears,polyunsaturatedfattyacidssuch as docosahexaenoic acid (DHA) andicosapentaenoicacid(EPA)haveattractedwideinterestbecauseoftheirdiversebutprominentbiologicalfunctions.Thesefattyacidsusualyhavecarbonnumbersof18-22.Ontheotherhand,anumberofratherlesscommonunsaturatedfattyacidshavebeendiscoveredwhosecarbonchainlengtharelongerby2-34ormorecarbonatomsthanabundantones.Thesefattyacidsarecaledverylongchainfattyacids(VLCFA)andarefoundmostlyasglycerophospholipidsandsphingolipidsinthematuresupermatozoaofanumberofmammalianspecies,theretina,thehumanbrainetc.??Also,VLCFA ofn-6serieswere reported to occurin ratseminiferoustubules.??Studiesontheirbiologicalroleshavejuststartedandthusitisessentialtodevelopsynthetic methods for preparing thesebiomoleculessinceitisnoteasytoisolatetheminapurestateandinalargeamountfrom thecomplexmixturesofbiologicalmaterials.Withthisinmind,asyntheticrouteforaphospholipidbearingtwokindsofpolyunaturatedfattyacylgrouphasbeendevelopedbyus,andstereo-chemicalassignmentoftheasymmetriccarbonwasalsoconducted??.Therouteforthestereo-chemicalassignmentstartsfromlipase-catalyzedstereoselectivemono-acylationof2-O-methox-yethoxymethylglycerol1(2-O-MEMG)toaffordanopticalyactivemonoacylglycerol2.Todetermineopticalpurityandconfigurationoftheasymmetrc carbon,this chiralglycerolwasconverted to 1-acyl-2,3-di-O-MEMG(notshown)folowedbyreductivecleavageoftheestergroupatthesn-1positiontogive2,3-di-O-MEMG.Wedeterminatedtherelationbetweenitsopticalrotationanditsstereochemicalconfig-urationaswelasitsopticalpurity??.Theiraccu-racyandreliability,however,werenotsatisfac-tory,since1and2withanumberofoxygenatomswerefoundtobeveryhygroscopicanditwasthereforedifficulttodeterminetheiraccu-rateweight.Inherentlylowspecificrotationof25ScientificReportsoftheFacultyofAgricultureOkayamaUniversityVol. , - ( )ReceivedOctober1,2000a)GraduateSchoolofScienceandTechnology,OkayamaUniversity,Tsushimanaka,Okayamab)DivisionofAppliedLifeScience,GraduateSchoolofAgriculture,KyotoUniversity,Kitashirakawa,Sakyo-ku,Kyoto606-8502,Japanalsohaspreventedactiveglycerophospholipidsbearingpolyunsaturatedfattyacylgroupatsn-1and2positions.Thiscommunicationdescribesadifferentrouteas shown in the scheme. First, t-butyldimethylsilyl (TBDMS) group wasintroducedtothehydroxygroupatsn-3positioninanopticalyactivemonoacylglycerol2withunknownstereochemistry.Asanextstep,weattemptedtocleavetheestergroupatsn-1posi-tionreductivelywithlithiumaluminum hydrideormethylmagnesium bromide.Unfortunately,however,theformeraffordedacomplexreactionmixtureandthelatter,noreaction.Wefoundthatsodium borohydridecouldcleavetheesterlinkagesmoothly.Thisunusualreactivity ofsodium borohydridewassupposedtobeduetothepresenceoftheMEM groupwithoxygenatomssuchascrownetherswhoselonepairmayinteractwithNa?,alowingactivationofthehydrideanions.Althoughthestereochemistryoftheglycerolderivative4freefromacylgroupatsn-1positionwasunknown,thesamecompoundcouldbeobtainedfrom 1-stearoyl-2-O-MEMGvia an intermediate 5 with known stereo-chemicalconfiguration(S)andopticalpurity(80% o.p.).Theconfigurationwasdeterminedpreviously by the stereochemicalcorrelationfrom 2-O-benzyl-1-stearoyl-sn-glycerol withknownstereochemistry.??Theopticalpurityof6was,however,notsoreliableastobeabletobeusedforthedeterminationoftheopticalpurityof4.Therefore,theopticalpurityof6wasfurtherconfirmedbyconvertingittoanMTPAesterandmeasuringthediastereomericratiobyTLCanal-ysis.Thus,6wasconvertedto4whichafforded［α］?＝＋14.3°(CHCl3),80％ o.p.withR-configu-ration.Therefore,6with100％ o.p.shouldhave［α］?＝＋or-17.9°(CHCl3)withR-orS-configura-tion,respectively.Usingthisvalue,thestereo-chemistryof4fromunknown2couldbedeter-minedbythiscorrelationsincetheremaybenopossibilityofracemizationatsn-2carbonineachreactionstepfrom6to4and2to4.Thus,2aand2bwerefoundtohave～100％ o.p.withR-configurationand95％ o.p.withR,respectively.Obviously,theestablished maximum specificrotationandtheconfigurationfor4canbeusedtodeterminetheopticalpurityandstereochemis-tryof2withanydifferentacylgroupatsn-1position.Experimental?H NMR spectra(δH)wererecordedonaVarianVXR200or500spectrophotometer,ionspraymassspectraweretakenwithanAPIⅢtriplequadrupolemassspectrometerequippedwithanionsprayinterface(PE-Sciex),andopti-calrotationswereonapolarimeter,modelJ-720(JapanOptics).1-Icosadienoyl-2-O-MEM-sn-glycerol(2a)?A mixtureoftrifluoroethylicosadienoate(150mg,0.4mmol)and2-O-MEM-glycerol(72mg,0.4Morietal. Sci.Rep.Fac.Agr.OkayamaUniv.Vol.Scheme1 ConversionofOpticalyActiveMonoacylg-lycerol1,2withUnknownStereochemistryand6 withKnownStereochemistrytoaCommonProduct4 withoutUnsaturatedFattyAcylGroup.i.RCOOCF?,LipasePS;i.Dimethy-t-butylsilylChloride,Imidazole inDMF;ii.Sodiumborohydride.6mmol)wasdissolvedindistileddisopropyletheraftercompleteremovalofmoisturefrom theesterinvacuo.LipasePS(100mg,AmanoPhar-maceuticalCo,Japan)wasaddedandthesolu-tionwasstirredat0°Cinanitrogenatmosphereinthedarkfor3h.Afterthisperiod,theenzymewasremovedbyfiltrationandtheresidueaftersolventevaporationwaschromatographedonsilicagel(hexane/ethylacetate,7:3)affording2ainalmostquantitativeyield(220mg).TLC(hexane/ethylacetate,6:4):Rf＝0.20.?H NMR (500MHz,CDCl3):δ5.35(m,8H,CH＝CH×2),4.81(m,2H,OCH2O),4.20-3.80(m,5H,(1-3)-H),3.65(m,2H,OCH2CH2O),3.60(m,2H,OCH2CH2O),3.40(s,3H,OCH3),2.78(t,J＝0.7,2H,CH＝CHCH2CH＝CH),2.35(dd,J＝7.9,7.9,2H,α-CH2),2.05(q,J＝15.5,4H,CH2CH＝CHCH2CH＝CHCH2),1.60(m,2H,β-CH2),1.50(m,18H,4’-9’,17’-18’and19’-CH2×9),0.88(t,J＝7.6,3H,ω-CH3)1-Arachidonoyl-2-O-MEM-sn-glycerol (2b)??H NMR (200MHz,CDCl3):δ5.35(m,8H,CH＝CH×4),4.83(s,2H,OCH2O),4.27-3.45(m,7H,OCH2CH2Oand(1-3)-H),3.38(s,3H,OCH3),2.80(dd,J＝4.5,11.8,6H,CH＝CHCH2CH＝CH),2.33(m,2H,α-CH2),2.06(m,4H,4’andCH2CH＝CH×2),1.62(m,2H,β-CH2),1.30(m,6H,17’-19’-CH2×3),0.88(t,J＝6.4,3H,ω-CH3)1-Icosadienoyl-2-O-MEM-3-O-TBDMS-sn-glycerol(3a)??HNMR(200MHz,CDCl3):δ5.35(m,4H,CH＝CH×2),4.75(s,2H,OCH2O),4.20-3.90(m,5H,(1-3)-H),3.65(m,2H,OCH2CH2O),3.47(m,2H,OCH2CH2O),3.38(s,3H,OCH3),2.76(dd,J＝7.2,7.2,6H,CH＝CH＝CH2CH＝CH),2.31(m,2H,α-CH2),2.04(q,J＝7.3,4H,CH2CH＝CHCH2CH＝CHCH2),1.62(m,2H,β-CH2),1.30(m,18H,4’-9’and17’-19’-CH2×9),0.85(m,12H,ω-CH3 and OSi(CH3)2(CH 3)3),0.03 (s,6H,OSi(CH3)2)2-O-MEM-3-O-TBDMS-sn-glycerol(4)?Amixtureof2a(140mg,0.26mmol)andNaBH4(15mg,0.39mmol)inmethanol(5ml)wasrefluxedfor1day.Afterthereaction,water(3ml)wasaddedandtheproductwasextractedwithdiethylether3times.Afterremovingthesolvent,theresiduewaschromatographedonsilicagel(hex-ane/ethylacetate,7:3)togive4in61% yield.TLC (hexane/ethyl acetate,8:2):Rf＝0.18.?HNMR (500MHz,CDCl3):δ4.80(s,2H,OCH2O),3.85-3.40(m,7H,OCH2CH2Oand(1-3)-H),3.38(s,3H,OCH3),0.8(s,9H,OSi(CH3)2C(CH3)3),0.03(s,6H,OSi(CH3)2)1-Linoleoyl-2-O-MEM-3-O-TBDMS-sn-glycerol(5)??HNMR(500MHz,CDCl3):δ5.35(m,5H,CH＝CH×2),4.80(s,2H,OCH2O),4.20-4.05(m,5H,(1-3)-H),3.75(m,2H,OCH2CH2O),3.70(m,2H,OCH2CH2O),2.76(t,J＝7.5,2H,CH＝CHCH2CH＝CH),2.31(m,2H,α-CH2),2.04(q,J＝7.5,2H,CH2CH＝CHCH2CH＝CHCH2),1.62(m,2H,β-CH2),1.30(m,14H,4-7’and15’-17’-CH2×7),0.88(m,12H,18’-H and OSi(CH3)2(CH3)3),0.03(s,6H,OSi(CH3)2(CH3)3)１-Arachidonoyl-2-O-MEM-3-O-TBDMS-sn-glycerol(3b)??H NMR(200MHz,CDCl3):δ5.35(s,8H,CH＝CH×2),4.80(s,2H,OCH2O),4.20-4.00 (m,5H,(1-3)-H),3.65 (m,2H,OCH2CH2O),3.47(m,2H,OCH2CH2O),3.38(s,3H,OCH 3),2.88 (dd,J＝5.0,13.0,CH＝CHCH2CH＝CH),2.31(dd,J＝8.0,8.0,2H,α-CH2),2.06(m,4H,CH2CH＝CH×2),1.62(m,2H,β-CH2),1.30(m,6H,17’-19’-CH2),0.80(s,12H,20’andOSi(CH3)2(CH3)3),0.03(s,6H,OSi(CH3)2)AcknowledgementWearegratefultoSCRNMRsystem(500and200MHz),OkayamaUniversity.References１)Zhang,H.,N.N.Desai,A.Olivera,T.Seki,G.Broo-ker,andS.Spiegel:Sphingosin-1-Phosphate,anovellipid,involvedincelularproliferation.J.Cel.Biol.,,155-167(1991)２)Desai,N.N.,H.Zhang,A.Olivera,M.E.MattieandS.Spiegel:Sphingosine-1-phosphate,ametaboliteofsphingosine,increasesphosphatidicacidlevelsbyphospholipaseDactivation.J.Biol.Chem., ,23122-23128(1992)３)Haider,S.S.,M.Tanaka,Md.K.Alam,S.Nakajima,February2001 StereochemicalDeterminationof2-O-Methoxyethoxymethylglycerol 7N.BabaandS.Shimizu:Synthesisofphosphatidyl-cholinehavingaverylongchainpolyunsaturatedfattyacid,Chem.Let.,175-176(1998)４)Baba,N.,T.Akiyama,S.TaharaandS.Nakajima:Short-routesynthesisofaglycerophospholipidbear-inganunsaturatedacylgroupatthesn-1position.Biosci.Biotecnol.Biochem., ,353-354(1995).５)Baba,N.,K.Yoneda,S.Tahara,J.Iwasa,T.KanekoandM.Matsuo:Aregioselective,stereoselectivesyn-thesisofadiacylglycerophosphocholinehydroperox-idebyuseoflipoxygenaseandlipase.J.Chem.Soc.,Chem.Commun.,1281-1282(1990)Sn-1位に多価不飽和脂肪酸を結合する2-O-methoxyethoxymethylglycerolの立体配置決定松本好太郎・森 義裕??・中島 修平・馬場 直道清水 昌??（岡山大学農学部生物資源化学講座）自然界に広く存在し，重要な生理機能を担っている多価不飽和脂肪酸結合リン脂質の化学的合成に必要な出発原料としての２-O-methoxyethoxymethylglycerolの立体配置と光学純度を，立体配置・光学純度既知の物質に化学的に誘導し，それらの比旋光度をお互いに比較する事により決定した．a)岡山大学大学院自然科学研究科生命分子科学専攻b)京都大学大学院応用生命科学専攻8 Morietal. 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Sn-1位に多価不飽和脂肪酸を結合する2-0-methoxyethoxymethylglycerolの立体配置決定

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Sn-1位に多価不飽和脂肪酸を結合する2-0-methoxyethoxymethylglycerolの立体配置決定

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