Asymmetric Epoxidation Of Dihydronaphthalene With A Synthesized Jacobs :: essays research papers

Asymmetric Epoxidation of Dihydronaphthalene with a Synthesized JacobsensCatalystAbstract. 1,2 diaminocyclohexane was reacted with L-(+)-tartaric acid to yield(R,R)-1,2-diaminocyclohexane mono-(+)-tartrate salt. The tartrate salt was thenreacted with super acid carbonate and 3,5-di-tert-butylsalicylaldehyde to yield(R,R)-N,N-Bis(3,5-di-tert-butylsalicylidene)-1,2-cyclohexanediamine, which wasthen reacted with Mn(OAc)2*4H2O and LiCl to form Jacobsens throttle. Thesynthesized Jacobsens catalyst was used to catalyze the epoxidation ofdihydronaphthalene. The products of this reaction were isolated, and it wasfound that the product yielded 1,2-epoxydihydronaphthalene as well asnaphthalene.IntroductionIn 1990, professor E.N. Jacobsen reported that chiral manganesecomplexes had the ability to catalyze the asymmetric epoxidation ofunfunctionalized alkenes, providing enantiomeric excesses that regularlyreaching 90% and sometimes exceeding 98% . The chiral manganese complexJacobsen utilised was (R,R)-N,N-Bis(3,5-di-tert-butylsalicylidene)-1,2-cyclohexanediaminato-(2-)-manganese (III) chloride (Jacobsens Catalyst).(R,R) Jacobsens Catalyst Jacobsens catalyst opens up short pathways toenantiomerically pure pharmacological and industrial products via thesynthetically versatile epoxy function .In this paper, a synthesis of Jacobsens catalyst is performed (Scheme1). The synthesized catalyst is then reacted with an unfunctional alkene(dihydronaphthalene) to form an epoxide that is highly enantiomerically enriched,as well as an oxidized byproduct.Jacobsens work is important because it presents both a reagent and amethod to selectively guide an enantiomeric catalytic reaction of industrialand pharmacological importance. Very few reagents, let alone methods, areknown to be equal to perform such a function, which indicates the trulygroundbreaking importance of Jacobsens work.Experimental SectionGeneral Protocol. 99% L-(+)- Tartaric Acid, ethanol,dihydronaphthalene and glacial a cetic acid were obtained from the Aldrich chemic Company. 1,2 diaminocyclohexane (98% mix of cis/trans isomers) andheptane were obtained from the Acros Chemical Company. Dichloromethane andpotassium carbonate were obtained from the EM Science division of EM Industries,Inc. Manganese acetate was obtained from the Matheson, Coleman and BellManufacturing Chemists. Lithium chloride was obtained form the JT bakerChemical Co. Refluxes were carried out using a 100 V heating mantle (Glas-ColApparatus Co. 100 mL, 90 V) and 130 V Variac (General Radio Company). senselessnessfiltrations were performed using a Cole Parmer Instrument Co. Model 7049-00aspirator pump with a Bchner funnel. For Thin Layer Chromatography (TLC)analysis, precoated Kodak chromatogram sheets (silica gel 13181 withfluorescent indicator) were used in an ethyl acetate/hexane (14) eluent.TLCs were visualized using a UVP Inc. Model UVG-11 Mineralight Lamp (Short-waveUV-254 nm, 15 V, 60 Hz, 0.16 A). Masses were taken on a Me ttler AE 100. Rotaryevaporations were performed on a Bchi Rotovapor-R. Melting points weredetermined using a Mel-Temp (Laboratory Devices, USA) equipped with a Fluke 51digital thermometer (John Fluke Manufacturing Company, Inc.). Optical rotations(aD) were measured on a Dr. Steeg and Renter 6mbH, Engel/VTG 10 polarimeter.