129801-01-0Relevant articles and documents
A general synthesis of methylenecyclopentanes by a stereoselective [3 + 2] approach
Ghera, Eugene,Yechezkel, Tamar,Hassner, Alfred
, p. 4959 - 4966 (2007/10/03)
The [3 + 2] cyclopentanation involving 3-(phenylsulfonyl)-2-(bromomethyl)-1-propene (1) and representative (E) α,β-unsaturated acyclic esters and ketones has been studied. High yields and complete stereoselectivity were observed in all reactions leading to tri- or tetrasubstituted methylenecyclopentanes. The anti-diastereoselectivity in the first, Michael addition step is rationalized by a chelation-controlled transition state in which MO interactions of the two π systems are involved. The Michael reactions of methallyl sulfone 8 with (E) enoates in the absence and presence of HMPA confirms the influence of chelation on the diastereomeric ratio of adducts. Cyclopentanations involving 1 with cyclohexenone, 2(5H)-furanone, and 5,6-dihydro-2-pyranone, respectively, were also studied with emphasis on the factors influencing the stereochemical outcome of the annulation process.
A new diastereoselective 3+2 annulation approach to five-membered carbocycles
Ghera,Yechezkel,Hassner
, p. 3653 - 3656 (2007/10/02)
The newly prepared 1-bromo-2-methylene-3-phenylsulfonylpropane 2 reacts with α,β unsaturated esters in a Michael induced ring closure to provide cyclopentane derivatives with complete diastereoselectivity.
