Reaction of the ruthenium allenylidene complex [Ru]dCdCdCPh 2 (1, [Ru] = Cp(PPh 3 ) 2 Ru) with the propargylic Grignard reagent R-CtCCH 2 MgBr (R = CH 3 , CH 2 CH 3 , Ph) yielded a mixture of two acetylide complexes. The major products, [Ru]CtCCPh 2 C(R)dCdCH 2 (2a, R = CH 3 ; 2b, R = CH 2 CH 3 ; 2c, R = Ph), have an allenyne moiety, and the minor ones, [Ru]CtCCPh 2 CH 2 CtCR (3a, R = CH 3 ; 3b, R = CH 2 CH 3 ; 3c, R = Ph), have a diyne ligand. The reaction of similar propargyl Grignard reagent HCtCCH 2 MgBr with 1 yielded only the diyne complex 3d. Treatment of complexes 2a-2c with HBF 4 afforded the cyclization complexes 5a-5c, respectively, proceeding via a vinylidene intermediate. The cyclization of the allenyl and the vinylidene groups is accompanied with a phenyl group migration. Complex 5b is fully characterized by a single-crystal X-ray diffraction analysis. Similar cyclization of complexes 2a and 2b, catalyzed by a Au phosphine complex, gave the ruthenium vinylidene complexes 6a and 6b, respectively, with different selectivity from that of the protonation reaction. Au-catalyzed cyclization of the diyne complex 3d yielded 6d, which is fully characterized by a single-crystal X-ray diffraction analysis.
Consecutive cyclization reactions of phenyl propargyl alcohols 1 and 2 are catalyzed by [Ru]NCCH(3)(+) ([Ru] = Cp(PPh(3))(2)Ru) in cosolvent CHCl(3)/MeOH at 60 °C, to afford the fused cyclic compounds 11a (R = Me) and 10a (R = Me), respectively.
The reactions of [Cp(PPh(3))(2) RuCl] (Cp=cyclopentadienyl) with phenyl propargylic alcohol 1a, with a 3-thiophene group, are explored. The carbene complex 2a, obtained exclusively from this reaction at low temperature, contains the naphthothiophene group, which is formed through a new cyclization process between the thiophene group and the inner carbon of the triple bond. Details of this process have been revealed by conducting the reaction at room temperature, affording the allenylidene complex 3a as a side product. Complex 3a is not converted into 2a, indicating that the cyclization takes place while the triple bond is π coordinated to the metal center. Complex 2a reacts with oxygen in the presence of NEt(3) at room temperature to afford, in high yield, naphthothiophene aldehyde 4a, ONEt(3), OPPh(3), and [Cp(PPh(3))(2)RuCl]. Molecular O(2) is likely activated by coordination to the metal center when one of the phosphane ligands dissociates. Then, NEt(3) promotes the oxygenation process by reacting with the coordinated O(2) to afford ONEt(3) and possibly an unobserved oxo-carbene complex. Coupling of the oxo and carbene ligands then yields 4a and [Cp(PPh(3))(2) RuCl] in CHCl(3). In a solvent system containing MeOH, the oxygenation reaction affords a mixture of 4a and naphthothiophene ester 5a-1. The reactions of [Cp(dppf)RuCl] (dppf=1,1'-bis(diphenylphosphino)ferrocene) with 1a, also afford the carbene complex 2a', 4a, and 5a, which have been characterized by X-ray diffraction analyses. For the phenyl propargylic alcohol 1b, with a 2-thiophene substituent, different naphthothiophene aldehyde and ester compounds are also obtained in high yields through a similar cyclization process followed by oxygenation under mild conditions.
The reaction of [Ru]-Cl ([Ru] = Cp(PPh3)2Ru) with o-ethynyl-substituted methyl benzoate, followed by a sequential deprotonation and electrophilic alkylation reactions by further reacting with base and various alkyl haloacetates, respectively, generated several disubstituted ruthenium vinylidene complexes. In the deprotonation reactions of these disubstituted vinylidene complexes containing two ester groups, tandem cyclizations of the ligand is accompanied with a methanol elimination to generate a new organometallic product containing a three-ring indenofuranone ligand, which structure has been confirmed by a single-crystal X-ray diffraction analysis. Facile protonation and methylation are observed in these indenofuranone complexes. Additionally, for the simple furyl complex containing an O-benzyl group, a 1,3-migration of the benzyl group is observed to yield a lactone product and a Claisen rearrangement is also observed in analogous complexes with O-allyl or O-propargyl groups.
Three new aristololactam derivatives, aristololactam W-Y (1-3), and three known compounds (4-6) were isolated from the fruits of Aristolochia contorta Bunge. Compounds 1 and 2 represent the first example of an N-CHOCH aristololactam derivative from natural products. Their structures were elucidated by 1D/2D NMR and HRESIMS spectra. All of the isolated compounds were evaluated for their insecticidal activity against 4th instar larvae of Aedes aegypti. Compound 4 displayed insecticidal activity with LC value of 3.54 μg/mL.
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