A new methodology of intramolecular hetero Diels–Alder reaction with β-alkoxy-substituted conjugated nitroalkenes as heterodienes: stereoselective one-pot synthesis of trans-fused bicyclic γ-lactones
作者:Eiji Wada、Masahiko Yoshinaga
DOI:10.1016/j.tetlet.2003.08.106
日期:2003.10
Tandem reaction of (E)-1-ethoxy-2-nitroethylene with δ,ε-unsaturated alcohols leading to stereoselective trans-fused bicyclic γ-lactones has been developed using a catalytic amount of a Lewis acid such as Yb(OTf)3 and Ni(ClO4)2·6H2O. This process involves the stereoselective tandem transetherification–intramolecular heteroDiels–Alderreaction leading to bicyclic nitronates, and sequential transformation
Nitroacetylene (1) was prepared by the reaction of NO2PF6 with trimethylsilylacetylene. It is stable at room temperature in dilute solution for about a week. The 1H and 13C NMR spectra of nitroacetylene reveal strong 1H-14N and 13C-14N spin couplings. Nitroacetylene reacts rapidly with nucleophiles. It gives a 1,4-Diels-Alder adduct with cyclopentadiene. However, its reactions with furan and vinyl ethers produce nitrovinylisoxazoles by a mechanism thought to involve the 1,4-addition of nitroacetylene to the vinyl ether to give a highly strained unsaturated nitrone, followed by fragmentation of the nitrone to vinyl nitrile oxide, then additions of this 1,3-dipolarophile.
1,4-Conjugate addition of the reformatsky reagent to α-nitrostyrenes: A new synthesis of γ-nitroesters.
作者:Rita Menicagli、Samaritani Simona
DOI:10.1016/0040-4020(95)00968-x
日期:1996.1
alpha-Nitrostyrenes react with the Reformatsky reagent to yield the corresponding 1,4-addition products. The reaction represents a practical and convenient route to ethyl 3-aryl-4-nitrobutanoates.