A new rhodium catalyzed ring opening reaction of oxabenzonorbornadienes and its derivatives was described. This reaction forms a new carbon-nitrogen bond via an intermolecular allylic displacement of the bridgehead o...A new rhodium catalyzed ring opening reaction of oxabenzonorbornadienes and its derivatives was described. This reaction forms a new carbon-nitrogen bond via an intermolecular allylic displacement of the bridgehead oxygen with a piperazine's derivatives, which proceeds with very high regioselectivity.展开更多
The signals of 1H NMR and 13 C NMR for benzodiheteropine 1 and its cycloaddtion products 2～5 were assigned by two dimensional NMR techniques. The characteristics of their structures were analyzed and ...The signals of 1H NMR and 13 C NMR for benzodiheteropine 1 and its cycloaddtion products 2～5 were assigned by two dimensional NMR techniques. The characteristics of their structures were analyzed and discussed. The boat conformation of the seven membered heteroatomic ring in these structures was interpreted on the basis of the spectrum of NOESY as well. The coupling constants of relative protons were in accord with above results.展开更多
1,2-rearrangements of carbenes :CCH_2X(X=CH_2, NH and O) are studied by using ab initio gradient method. Heteroatoms N and O stabilize the carbene and decrease its reactivity, mainly by changing frontier molecular orb...1,2-rearrangements of carbenes :CCH_2X(X=CH_2, NH and O) are studied by using ab initio gradient method. Heteroatoms N and O stabilize the carbene and decrease its reactivity, mainly by changing frontier molecular orbitals, but retain the way of the reaction. The reaction starts from the attack of the migrating hydrogen on the carbene p AO and ends with the entrance of the hydrogen into the carbene σ orbital. Reactivities are in the order of X=CH_2>NH>O. The reaction is exothermic or endothermic according to whether the product is a 4n+2 or 4n π electron molecule.展开更多
Metallaaromatics are metallacycles that are derived from the formal replacement of a carbon atom in the framework of organic aromatics with a metal fragment. As an important subclass of metallaaromatics, metallaaromat...Metallaaromatics are metallacycles that are derived from the formal replacement of a carbon atom in the framework of organic aromatics with a metal fragment. As an important subclass of metallaaromatics, metallaaromatics that contain main-group heteroatoms have attracted considera- ble attention. In the past ten years, we have developed several new methods to construct metallaaromatics as well as those containing main-group het- eroatoms, such as metallapyridine, metallapyridinium, metallapyridyne, metallafuran, metallabenzothiazole, metallabenzoxazole, metallabenzthiophene, aza-metallapentalene and some novel tricyclic/tetracyclic metallaaromatics. In addition, interesting reactions such as the first hetero-Diels Aider reaction between 1-metalla-1,3-dienes and nitriles, the first intramolecular nucleophilic aromatic substitution （SNAr） reaction of metallabenzene, and the first iodine-mediated electrophilic cyclizations of a metallabenzene complex were demonstrated. In this account, recent and novel approaches for their synthesis and property analyses are summarized. The structural diversity and unique properties of metallaaromatics containing main-group heteroatoms will strongly inspire further investigation of these species and provide a wide range of potential applications.展开更多
文摘A new rhodium catalyzed ring opening reaction of oxabenzonorbornadienes and its derivatives was described. This reaction forms a new carbon-nitrogen bond via an intermolecular allylic displacement of the bridgehead oxygen with a piperazine's derivatives, which proceeds with very high regioselectivity.
文摘The signals of 1H NMR and 13 C NMR for benzodiheteropine 1 and its cycloaddtion products 2～5 were assigned by two dimensional NMR techniques. The characteristics of their structures were analyzed and discussed. The boat conformation of the seven membered heteroatomic ring in these structures was interpreted on the basis of the spectrum of NOESY as well. The coupling constants of relative protons were in accord with above results.
基金This project was supported by the National Natural Science Foundation of China.
文摘1,2-rearrangements of carbenes :CCH_2X(X=CH_2, NH and O) are studied by using ab initio gradient method. Heteroatoms N and O stabilize the carbene and decrease its reactivity, mainly by changing frontier molecular orbitals, but retain the way of the reaction. The reaction starts from the attack of the migrating hydrogen on the carbene p AO and ends with the entrance of the hydrogen into the carbene σ orbital. Reactivities are in the order of X=CH_2>NH>O. The reaction is exothermic or endothermic according to whether the product is a 4n+2 or 4n π electron molecule.
基金This work was financially supported by the National Natural Science Foundation of China （21332002 and 21561162001）.
文摘Metallaaromatics are metallacycles that are derived from the formal replacement of a carbon atom in the framework of organic aromatics with a metal fragment. As an important subclass of metallaaromatics, metallaaromatics that contain main-group heteroatoms have attracted considera- ble attention. In the past ten years, we have developed several new methods to construct metallaaromatics as well as those containing main-group het- eroatoms, such as metallapyridine, metallapyridinium, metallapyridyne, metallafuran, metallabenzothiazole, metallabenzoxazole, metallabenzthiophene, aza-metallapentalene and some novel tricyclic/tetracyclic metallaaromatics. In addition, interesting reactions such as the first hetero-Diels Aider reaction between 1-metalla-1,3-dienes and nitriles, the first intramolecular nucleophilic aromatic substitution （SNAr） reaction of metallabenzene, and the first iodine-mediated electrophilic cyclizations of a metallabenzene complex were demonstrated. In this account, recent and novel approaches for their synthesis and property analyses are summarized. The structural diversity and unique properties of metallaaromatics containing main-group heteroatoms will strongly inspire further investigation of these species and provide a wide range of potential applications.
