Cyclization/Dmierization Reactions of Ruthenium Complex with Substituted N-Propargyl Pyrroles and Aryl Alkynes Containing o-Carbonyl Group

• Main Authors: Pi-Yeh Chia, 賈丕業
• Other Authors: 林英智
• Format: Others
• Language: zh-TW
• Published: 2016
• Online Access: http://ndltd.ncl.edu.tw/handle/v9q4m8

博士 === 國立臺灣大學 === 化學研究所 === 107 === Ch1:In our investigation on the chemical reactions of N-propargyl pyrroles 1a-c containing aldehyde, keto and ester group on the pyrrole ring with [Ru]-Cl ([Ru] = Cp(PPh3)2Ru), an aldehyde group in the pyrrole ring is found to play a crucial role to stimulate cyclization reaction. The reaction of 1a containing an aldehyde group with [Ru]-Cl in the presence of NH4PF6 yields the vinylidene complex 2a which further reacts with allyl amine to give the carbene complex 6a with a pyrrolizine group. However, if 1a is first reacted with allyl amine to yield the iminenyne 8a, then the reaction of 8a with [Ru]-Cl in the presence of NH4PF6 yields the ruthenium complex 9a containing cationic pyrrolopyrazinium group, fully characterized by X-ray diffraction analysis. These results can be adequately explained by two processes after the triple bond of the propargyl group is coordinated to the Ru metal center. Namely, competing formation of a vinylidene intermediate vs direct nucleophilic attack control the reaction pathway. Additionally deprotonation of 2a by R4NOH yields the neutral acetylide complex 3a. In the presence of NH4PF6, attempted alkylation of 3a resulted in the formation the Fischer-type amino-carbene complex 5a due the presence of NH3 serving as a nucleophile. Using KPF6, alkylations of 3a with ethyl- and benzyl-bromoacetates afforded the disubstituted vinylidene complexes 10a and 11a containing ester groups, which underwent deprotonation reactions to give the furyl complexes 12a and 13a, respectively. For 13a containing an O-benzyl group, a subsequent 1,3-migration of the benzyl group is observed to yield the product 14a with a lactone unit. Similar reactivity was not observed for the corresponding N-propargyl pyrroles 1b and 1c containing keto and ester groups on the pyrrole ring. Ch2:A remarkable intermolecular dehydrative coupling reaction with formation of a C-C bond was found for the vinylidene complex 2a, yielding the dinuclear bisvinylidene complex 4a. Complex 2a containing 1-hydroxyindan moiety was first formed from the reaction of o-propynyl benzaldehyde 1a with [Ru]-Cl ([Ru] = Cp(PPh3)2Ru) by a cyclization process. For analogous aldehyde 1b containing an additional 1,3-dioxolane group on the aryl ring, similar intermolecular coupling yields the dinuclear bisvinylidene complex 4b. However, the fluoro group on the aryl ring in aldehyde 1c inhibits the coupling reaction, thus the reaction gives only the vinylidene complex 2c. For the reactions of [Ru]-Cl in MeOH with compounds 1f, 1g and 1h, each with a ketone functionality, cyclization gives the vinylidene complexes 2f, 2g and 2h, respectively. However, no similar intermolecular coupling was observed, instead, the intramolecular dehydration yields 8f, 8g and 8h, respectively. In CDCl3, catalytic cyclization is observed for the o-propynylphenyl ketone 1h with [Ru]-Cl at 50 °C giving the isochromene products 14h. Furthermore, treatment of the o-propynylaryl α,β-unsaturated ketones 1k-m and 1n with [Ru]-Cl in MeOH affords the corresponding vinylidene complexes 10k-m and 11n each with 1-benzosuberone moiety in the presence of NH4PF6. These intramolecular cyclization products are formed by the addition of Cβ onto the terminal carbon of the alkene moiety. All these reaction products are characterized by spectroscopic methods. In addition, structures of complexes 4a, and 10l are confirmed by single crystal X-ray diffraction analysis.