Metal-Free-Catalyzed Synthesis of Allyl Nitriles via C<sub>sp<sup>2</sup></sub>–C<sub>sp<sup>3</sup></sub> Coupling between Olefins and Azobis (Alkyl-carbonitrile)
The metal-free-catalyzed synthesis of allyl nitriles from Csp2-Csp3 coupling between olefins and azobis was carried out. Key on this work was that the synthesis of allyl nitriles directly using olefin as a starting material was considered to be more efficient and economical than the alkyne, alkynyl carboxylic acid, or cinnamic acid used in previous works. Moreover, in this reaction, iodine served as
Radically Initiated Asymmetric Cyclizations as Model Reactions for Asymmetric Cyclocopolymerizations
作者:Günter Wulff、Bernd Kühneweg
DOI:10.1021/jo970012b
日期:1997.8.1
The two divinyl compounds 3,4-O-cydohexylidene-D-mannitol 1,2;5,6-bis-O-[(4-vinylphenyl)boronate] (la) and 3,4-O-cyclohexylidene-D-mannitol 1,2;5,6-bis-O-[(4-vinylnaphthyl-1)boronate](lb) were cyclized by radical initiation either with an excess of 2,2'-azobis(isobutyronitrile) (AIBN) or with tributyltin hydride under radical-generating conditions. The cyclization products contained a 19-membered ring and were obtained in yields of around 60%. During this cyclization, two new stereogenic centers are formed and four stereoisomers are therefore possible. The composition could be determined quantitatively after removing the template, 3,4-O-cyclohexylidene-D-mannitol, and deboronation, thus furnishing 5-8. In this way the stereochemical course of the cyclization could be investigated in detail. The reaction is a good model for the stereochemical course of the cyclocopolymerization of monomers la or Ib with other comonomers such as methyl methacrylate. It was shown that with both monomers the first step shows low stereoselectivity, whereas the second step is highly stereoselective, which is the cause of the strong optical activity of the copolymers from la or Ib after removal, of the template.
The thermal decomposition of octyl nitrite in hydrocarbon solvents