Ethylene cycloisomerization

Incorporation of the carboxylic acid group into the substrate also had an effect on the stereochemistry of the Alder-ene products. Trost and Gelling60 observed diastereoselectivity in the palladium-catalyzed cycloisomerization of 1,7-enynes when the reactions were conducted in the presence of A,A-bis(benzylidene)ethylene diamine (BBEDA, Figure 2). They were able to synthesize substituted cyclohexanes possessing vicinal (Equation (53)) and... 

Palladium-lead-calcium carbonate quinoline Ethylene from acetylene derivatives with cycloisomerization... 

When enyne cycloisomerization takes place in the presence of an unsaturated molecule an insertion reaction can occur. Thus, the ruthenacyclopentene intermediate formed from Cp RuCl(cod) can undergo insertion of ethylene to give a ruthenacycloheptene. Subsequent p-hydride elimination led to cyclization products with a propenylidene substituent [101] [Eq. (41)]. Various carbo- and heterocyclic compounds were formed in good yields. 

R. Spina, E. Colacino, J. Martinez, F. Lamaty, Poly(ethylene glycol) as a reaction matrix in platinum- or gold-catalyzed cycloisomerization a mechanistic investigation, Chem. Eur. J. 19 (2013) 3817-3821. 

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