401 



Dibenzofurans and Related Substances 



dydymic acid would be formed by coupling of two similar 

 orsellinic acids: 



CH3CH,CH2 ^^^^ CHaCH,CH,CH,CH, ^^^^ 

 I COOH I COOH 



+ 



HO 



OH 



HO 



OH 



CH3CH2CH2 



P^ 



OH 



I 

 CO 



CH2CH2CH2CH2CH 



0|0 

 H 



COOH 



OH 



HvCsl^^ CaHu^QQ^ 



HO 



H7C3 



C5H11 



H7C3 



CsHii 



COOH 





HO 



And in the case of usnic acid: 



COOH 



OH CH3O O OH 



Didymic Acid 



H H 



O O 



CH3I COCH3 CH3 



+ 



HO I '-^ O 



COCH3 H 



%. 



HO I OH O 



COCH3 H 



i 

 H H H H 



00 00 



CH3 I CH,! COCH3 CH3 I r»J COCH3 



" ' — H2O ^ ' " ' 



COCH3 



Usnic Acid 



HO I O 



COCH3 H 



