The coordination chemistry of ring-contracted porphyrinoids,such as subporphyrins and calix[3]pyrroles,has been largely unexplored owing to the synthetic difficulty of their free-base analogues.Here,we report strain-b...The coordination chemistry of ring-contracted porphyrinoids,such as subporphyrins and calix[3]pyrroles,has been largely unexplored owing to the synthetic difficulty of their free-base analogues.Here,we report strain-based molecular design and high-yield synthesis of thiazole-containing calix[3]pyrrole analogues for metal complexation.The artificial force induced reaction and StrainViz analysis methods were used to perform a conformational search and evaluate/visualize the ring strain.The results indicated that the thiazole-containing analogues are less strained than the parent calix[3]pyrrole,while incorporation of imidazole or oxazole unexpectedly leads to an increase in the total strain.Calix[1]furan[2]thiazole was obtained in 60%yield by the direct macrocyclization betweenα-bromoketone and bis(thioamide),whereas the meso-N(sp^(2))-bridged analogue,which was calculated to be 5.1 kcal mol^(−1)more strained,was only obtained in a 2%yield.Calix[1]furan[2]thiazole was converted to calix[1]pyrrole[2]thiazole to investigate metal complexation.Through the reaction with Et2Zn,calix[1]pyrrole[2]thiazole bound a Zn(Ⅱ)ion in a tridentate fashion adopting a cone conformation,giving a water/air stable organozinc complex that catalyzes polymerization of lactide.Conversely,Ag(Ⅰ)and Pd(Ⅱ)ions coordinated to the partial cone conformation of calix[1]pyrrole[2]thiazole in a bidentate fashion.Strain-based molecular design expands the synthetic access to contracted porphyrinoids and provides the opportunity to take advantage of their rich coordination chemistry.展开更多
基金partly supported by a JSPS Grant-in-Aid for Scientific Research(B)(No.22H02058)JST FOREST Program(No.JPMJFR211H),of which Y.Inokuma is the principal investigator+1 种基金partly supported by Toyota Riken ScholarNOASTEC Foundation to T.Y.
文摘The coordination chemistry of ring-contracted porphyrinoids,such as subporphyrins and calix[3]pyrroles,has been largely unexplored owing to the synthetic difficulty of their free-base analogues.Here,we report strain-based molecular design and high-yield synthesis of thiazole-containing calix[3]pyrrole analogues for metal complexation.The artificial force induced reaction and StrainViz analysis methods were used to perform a conformational search and evaluate/visualize the ring strain.The results indicated that the thiazole-containing analogues are less strained than the parent calix[3]pyrrole,while incorporation of imidazole or oxazole unexpectedly leads to an increase in the total strain.Calix[1]furan[2]thiazole was obtained in 60%yield by the direct macrocyclization betweenα-bromoketone and bis(thioamide),whereas the meso-N(sp^(2))-bridged analogue,which was calculated to be 5.1 kcal mol^(−1)more strained,was only obtained in a 2%yield.Calix[1]furan[2]thiazole was converted to calix[1]pyrrole[2]thiazole to investigate metal complexation.Through the reaction with Et2Zn,calix[1]pyrrole[2]thiazole bound a Zn(Ⅱ)ion in a tridentate fashion adopting a cone conformation,giving a water/air stable organozinc complex that catalyzes polymerization of lactide.Conversely,Ag(Ⅰ)and Pd(Ⅱ)ions coordinated to the partial cone conformation of calix[1]pyrrole[2]thiazole in a bidentate fashion.Strain-based molecular design expands the synthetic access to contracted porphyrinoids and provides the opportunity to take advantage of their rich coordination chemistry.
