3-phenylisoxazole 및 3-phenyl-2,5-dihydroisoxazol-5-one 유도체의 합성과 살균활성에 관한 구조-활성관계

Synthesis and quantative structure-activity relationships on the antifungal activity of 3-phenylisoxazol and 3-phenyl-2,5-dihydro-5-isoxazolone derivatives

기질 물질로서 일련의3-phenyl-2,5-dihyoisoxazol-5-one(A) 및3-phenylisoxazole(B)유도체는 친핵성 첨가-제거반응($Ad_{N-E}$)으로 (A)가 (B)보다 높은 수율로 합성되었으며 정량적인 구조와 저항성(PRC) 및 감수성(SPC) 고추역병균(Phytophthora capsici)에 대한 살균 활성과의 관계(QSAR)를 검토하였다. 두 균주에 대한 살균활성은 공통적으로 benzoyl고리에 결합된 치환기의 폭인 $B_2$ 상수의 적정값(약$4.0{\AA}$)에 의존적(RPC: $(B_2)_{opt.}=3.74{\AA}$ 및 SPC: $(B_2)_{opt.}=3.99{\AA}$)이었으며 치환기가 RPC에는 전자끌게로 작용한 반면에 SPC에는 전자 끌게로 작용하지 않았다. Free-Wilson 분석결과, RPC 및 SPC, 두 균주에 대한 살균활성은 (A)가 (B)보다 컸으며 할로겐과 acetyl-치환체가 기여하였고, RPC에는 cyano, methoxy 및 methyl-치환체 등이 선택적으로 기여하였다.

A series of new 2-benzoyl-3-phenyl-2,5-dihydroisoxazol-5-one, (A) and 3-phenyl-5-phenylcarbonyl-oxyisoxazole, (B) derivatives as substrates were synthesized and their quantitative structure-activity relationships (QSAR) analyses between the antifungal activities ($pI_{50}$) and physicochemical parameters of substituents onl the benzoyl group against resistant (RPC:95CC7303) and sensitive (SPC:95CC7105) Phytophthora blight (Phytophthora capsici,) were studied. The synthetic yield (%) and antifungal activities of (A) were higher than (B) and selectivities between the fungi were not showed. From the basis on the Hansch-Fujita analyses, the optimum width values ($(B_2)_{opt.}=ca.\;4.00{\AA}$) of the substituents on the benzoyl group were important factor in determining fungicidal activity against the two fungi. Influence of the substituents as electron withdrawing group on the fungicidal activity against RPC, but not for SPC. And tile bromo- and acetyl-substituents were contributed to higher antifungal activity against RPC and SPC from the results of Free-Wilson analyses.