SYNTHESIS OF THE K VITAMINS 839 



H OH 



"'■ f i'"' r- ?"■ r- i"' 



c ,c-ch,ch=cch,chxhxhch,chxh-6hch,ch,ch,chch3 — — 



\./ \ ;/ 2 2 2 2 2 2 2 ^ OR AgO 



H OH ZM 





H ^ 



"? n H^^' CH, CH3 CHj CH3 



I 11 II I I I I 



HC. C-CH2CH=CCH2CH2CH2CHCHjCH2CHjCHCHjCHjCH2CHCH3 



H H I 



Synthesis of Vitamin Ki 



The best yields of the vitamin were obtained when the reaction was car- 

 ried out in a sHghtly acid medium. In the presence of strong acids or min- 

 eral acids, a further condensation occurs, with the result that tocopheryl- 

 like compounds arise. In the presence of alkali, the yield is low, and it is 

 difhcult to separate vitamin Ki from the resulting brown mixture. 



Another synthesis involves the use of the alcohols, phthiocol and phytol, 

 according to the procedure of Tishler, Fieser, and Wendler.^^ The yield 

 is not as satisfactory as that obtained by the procedures described pre- 

 viously. 



(^) Synthesis of Vitamin K^ 



In view of the fact that the most potent antihemorrhagic agent is 2- 

 methyl-l,4-naphthoquinone, and that no advantage is to be gained by the 

 use of the natural vitamins Ki or K2, the synthesis of vitamin K2 is solely 

 of academic interest. As yet, no synthesis of vitamin K2 has been re- 

 ported. 



(3) Synthesis of Menadione 



Menadione, which is the recent name coined for 2-methyl-l,4-naphtho- 

 quinone, is made most simply by oxidation of 2-methylnaphthalene by 

 means of chromic acid in acetic acid^^"®^ at room temperatures below 

 50°C.,®^ by hydrogen peroxide, ^'^ or by air. As much as 30 to G0% of the 



58 M. Tishler, L. F. Fieser, and N. L. Wendler, /. Am. Chem. Soc, 62, 1982-1991 

 (1940). 



'9 K. Fries and W. Lohmann, Ber., 54, 2912-2924 (1921). 



^ R. J. Anderson and M. S. Newman, /. Biol. Chem., lOS, 405-112 (1933). 



" L. I. Smith and I. M. Webster, J. Am. Chem. Soc, 59, 662-667 (1937). 



«2 L. F. Fieser, W. P. Campbell, E. M. Fry, and M. D. Gates, J. Am. Chem. Soc, 61, 

 2o59, 3216-3223 (1939). 



" R. T. Arnold and R, Larson, J. Org. Chem., 5, 250-252 (1940). 



