Sg Tetronic Acids and Other Lactones and Lactams 



Cetraria islandica f. tenuifolia, Nephromopsis stracheyi 

 f. ectocarpisma Hue. 



Yasuhiko Asahina and Masaiti Yasue, Ber. 70B 1053 (1937). 



Yukio Kameda, /. Pharm. Soc. Japan 61 266 (1941). 

 (German abstract) 



157 d-Protolichesterinic Acid, C19H32O4, colorless leaflets, m.p. 107.5°, 



[2W +12.1°. 



HOOC CH2 



\ X 



CH C 



I I 



CH C 



CH3(CH2)l2 O 



Cetraria islandica Ach., Parmelia sinodensis Asahina, 

 Cladonia papillaria (Ehrh.) Hoffm. 



Yasuhiko Asahina, /. Japan. Botan. 18 489 (1942). 



The Z-isomer, m.p. 107.5°, [a]D'^^ -12.7°, has been iso- 

 lated from Cetraria crispa Nyl. (=C. tenuifolia Howe). 



Y. Asahina and M. Asano, J. Pharm. Soc. Japan No. 539, 1 

 (1927). 



Eugene E. van Tamelen and Shirley Rosenberg Bach, /. Am. 

 Chem. Soc. 80 3079 (1958). (Synthesis) 



158 f-aZio-Protolichesterinic Acid, C19H32O4, colorless plates, m.p. 



107°, [ocW^ -102°. 



Cetraria islandica Ach. var. orientalis Asahina 

 Yasuhiko Asahina and Masaiti Yasue, Ber. 70B 1053 (1937). 



159 Nephromopsic Acid, C19H34O4, colorless leaflets, m.p. 137°. 



HOOC CH3 



\ y 



CH CH 



I i 



CH C 



CH3(CHo)i2 '-' O 



Nephromopsis stracheyi f. ectocarpisma Hue. 

 Occurs with usnic acid, Michesterinic acid, Z-proto- 

 lichesterinic acid and caperatic acid. 



Michizo Asano and Tiaki Azumi, Ber. 68B 995 (1935). 



