BUTYLOXYCARBONYL-L-PROLINE

Department of Chemistry, Drexel University, Philadelphia, Pennsylvania, 19104. 

Submitted by Ulf Ragnarsson, Sune M. Karlsson, Bengt E. Sandberg, and Lars-Eric Larssok1 Checked by S. Wang and A. Brossi 

Erlenmeyer flask (Note 1) equipped with a magnetic stirrer, and a thermometer is charged with 115 g. (1.0 mole) of L-proline (Note 2) and 500 ml. of dimethyl sulfoxide (Note 3). To the stirred suspension are added simultaneously, over 5 minutes, 115 g. (1.0 mole) of 1,1,3,3-tetramethylguanidine (Note 4) and 214 g. (1.10 moles) of tert-butyl phenyl carbonate (Note 5). The proline dissolves completely within a few minutes in an exothermic reaction, the temperature of which reaches a maximum of 50-52° after 10-15 minutes. After stirring for 3 hours, the clear reaction mixture is transferred to a 6-1. Hcparatory funnel and shaken with 2.2 1. of water and 1.8 1. 

A three-necked flask equipped with a U-tube may also be used for the reaction. 

The submitters used L-proline obtained from Tanabe Seiyaku Company, Ltd., Osaka, Japan and checked its purity by the method of Manning and Moore.2 The L-proline used by the checkers was obtained from Ajinomoto Company, New York. 

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Racemic cw-l-amino-2-phenylcyclohexanecarboxylic acid 693 can be prepared by Diels-Alder reaction of (Z)-4-benzyhdene-2-phenyl-5(47/)-oxazolone 621 and butadiene in an analogous manner. Coupling A-tert-butyloxycarbonyl-L-proline with 693 yielded diastereomeric dipeptides that were separated chromatographi-cally. The behavior of the individual dipeptides was studied as a means to effect p-tum modulation by such cyclohexane analogues of phenylalanine. ... 

Cl2H2oClLiN408, Bis(cyclodisarcosyl)lithium perchlorate, 43B, 610 Cl2H20N2O5 r t-Butyloxycarbonylglycyl-L-proline, 43B, 610 Cl2H20N2O5S2 f t-Butyloxycarbonyl-L-cysteinyl-L-cysteine disulfide methyl ester, 43B, 612... 

S.2.6.2.. tert-BUTYLOXYCARBONYL Ougo(all-l-prolines) (CH3)3C0C0- -[N-CHCO] - -OH ... 

An Nitrone lassen sich Alkene 1,3-dipolar addieren. Dies nutzt eine asymmetrische Syn-these von L-5-Oxa-prolin aus. Das Nitron aus 2,3 5,6-Di-0-isopropyliden-mannose-oxim mit Glyoxylsaure-tert.-butylester in situ) cyclisiert mit Ethen, wobei das (JS)-Dihstereo-mer spontan kristallisiert (3R)- bzw. (3S)-3-tert.-Butyloxycarbonyl-2-(2,3 5,6-di-0-iso-propyliden-ct-D-mannofuranosyl) l,2-oxazolidin[9i%, 54% de (S43%].Nachder Abspaltung des Aldose-Restes erhalt man (S)-5-Oxa-prolin-tert.-butylester (3-tert.-Butyl-oxycarbonyl-1,2-oxazolidin 90% Schmp. 52-530)4 ... 

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