Reaction Studies On Methylenecyclopropane And Cyclopropenes

This dissertation is carried out on the reactions of two kinds of highly strained-ring componds, which includes methylenecyclopropanes (MCPs) and arylvinylcyclopropenes (AVCPs). These componds can be activated by acids or metal catalysts to generate cyclopropane cations and then undergo ring-opening reactions or can be captured by various reagents. Enlightened by these, we developed series of methodologies for building a variety of aromatic compounds and heterocyclic compounds.The dissertation is divided into three parts:the first one is an extention based on our group's previous studies on acid catalyzed reactions of methylenecyclopropanes, including Lewis acid catalyzed nucleophilic ring-opening of activated MCPs by oxygen atoms of the enolates derived from 1,3-diones to obtain homoallylic ethers (Chapter 1.1); Brφnsted acid and solid acid catalyzed Diels-Alder reaction of MCPs (as the dienophile) and imines to produce tetrahydroquinoline derivatives with retention of the three-membered rings (Chapter 1.2).The second part is the intramolecular/intermolecular reactions of a class of conjugate stabilized cyclopropene componds. These compounds can be easily prepared by thermal-rearrangement of vinylidenecyclopropanes (VDCPs), which have been well studied by our group before, under basic conditions in excellent isolated yields. According to the employ of varieties of acid/metal-catalysts and external reagents, different types of C-C bond cleavage of cyclopropenes took place to initiate rearrangement and addition reactions, which includes Brφnsted acid promoted addition of AVCPs with aldehydes to produce 5,6-dihydrobenzo[c]phenanthrene derivatives and Lewis acid promoted addition of AVCPs with acetals to yield dihydrocyclopenta[a]indene componds. We have proposed two reaction pathways, and verified these routes by computational chemistry (Chapter 2.1); Al(Ⅲ) catalyzed ring-opening of AVCPs and tandem Diels-Alder reactions with activated olefins which is the firstly reported appilication of cyclopropenes as pro-dienes not dienophiles, as well as Brφnsted acid catalyzed 1,4-addition reactions of AVCPs with activated olefins (Chapter 2.2); the first report Au(Ⅰ) catalyzed cycloisomerization of cyclopropenes (Chapter 2.3); Pd(Ⅱ) catalyzed tandem cycloisomerization and oxidation of AVCPs using p-benzoquinone (p-BQ) as oxidant and pro-nucleophile (Chapter 2.4); synthesis ofπ-allylpalladium complexes using AVCPs and stoichiometric amount of PdCl2(PhCN)2 and Ag(Ⅰ) and TfOH promoted further dehydrogenetive rearrangement of theπ-allylpalladium complexes to 7H-Benzo[c]fluorene derivatives (Chapter 2.5). The last part is the synthesis of a novel hetero-atom (N/O atom) tethered 1,6-cyclopropene-yne and a novel tandem ring-opening/ring-closing/cross-metathesis of 1,6-cyclopropene-ynes with olefins catalyzed by the first-generation Grubbs'ruthenium complex. The novel 1,6-cyclopropene-yne was prepared by Rhodium catalyzed mono-cyclopropenation of diynes. This synthetic protocol furnishes 3-pyrroline and 2,5-dihydrofuran derivatives straightforwardly. Several control; experiments reveal that the initiator of the reaction is alkylidenes not the common methylidene (Chapter 3).