307 



Something analogous was formerly proposed by Hartwall, l ) 

 who expected a one-sided synthesis by the reduction of the citraco- 

 nates and mesaconates of optically active alcohols, such as menthol 

 or borneol] but he did not make experiments in this direction. 



Kipping studied the addition of hydrogen to quinine-pymvate, 

 quinine-lev ulinate, bomyl-pyruvate, or to its oxime, and to bornyl- 

 benzoyl- formate ; however, his results were as negative as those of 

 Cohen and Whiteley. 



Because of technical difficulties Fischer and Slimmer's 

 attempts to produce a one-sided cyanohydrine-synihesis with helicine: 



H 



/C^p (C 2 H 3 0) 4 C 6 H 7 5 



C 6 H 4 (^ , and with tetracetyl-helicine: >0 



\OC 6 H 11 6 C 6 H 4 -C8, 



had at last to be given up. In the last case the apparently 

 positive result was produced by the admixture of a strongly 

 optically active condensation-product in the oxy-phenyl-ethyl-carbinol 

 finally obtained. 



Scholtz 2 ) started with N-methyl-a-pipecoline, and combined 

 laevogyratory amyl-iodide with it; the unattacked base, however, 

 proved to be absolutely inactive. 



In 1904 Marckwald, 3 ) starting with inactive methyl-ethyl- 

 malonic acid, finally obtained an optically active valeric acid in 

 the following way. 



He prepared from the first compound the acid brucine-salt , the 

 solution of which was evaporated and the less soluble product 

 separated from it. This was then heated to 170 C, carbon-dioxide 

 driven off, and the brucine removed from the residue. 



The valeric acid thus obtained was a mixture of the racemic 

 and of 10% of the laevogyratory acid. Tymstra 4 ) found, that 

 the final product yields more than 25% excess of laevogyratory 

 acid, if heating is done in vacuo; the temperature must in that 

 case not be higher than 100 120C. Cohen and Patterson 5 ) are 

 right in their criticism, when they contend that the first stage of 



x ) G. Hartwall, Inaug. Dissert., Helsingfors, (1904). 



2 ) M. Scholtz, Ber. d. d. Chem. Ges., 34, 3015, (1901). 



3 ) W. Marckwald, Ber. d. d. Chem. Ges., 37, 349, (1904). 



4 ) S. Tymstra Bzn., Ber. d. d. Chem. Ges., 38, 2165, (1905). 



5) J. B. Cohen and T. S. Patterson, Ber. d. d. Chem. Ges., 37, 1012, (1904); 

 W. Marckwald, ibid., 37, 1368, (1904). 



