ON THE STEREOCHEMICAL OUTCOME OF THE CATALYZED AND UNCATALYZED CYCLOADDITION REACTION BETWEEN ACTIVATED KETENES AND ALDEHYDES TO FORM CIS-2-OXETANONES AND TRANS-2-OXETANONES - AN AB-INITIO STUDY

The possible reaction paths corresponding to the catalyzed and uncatal yzed reaction between chloroketene (as a model activated ketene) and a cetaldehyde (as a model alkyl carbonyl compound) have been studied usi ng ae, initio methodologies and taking into account solvent effects. E ight transition structures have been located and characterized, both i n the gas phase and in solution. It has been found that formation of t rans-2-oxetanones is favored in the absence of catalyst, whereas the c atalyzed reaction leads to the preferential formation of the correspon ding cis cycloadducts. These results are in qualitative agreement with the experimental data available.