Abstract
A Molecular Electron Density Theory (MEDT) study is presented here for [3+2] cycloaddition (32CA) reactions of three trimethylsilyldiazoalkanes with diethyl fumarate. The presence of silicon bonded to the carbon of these silyldiazoalkanes changes its structure and reactivity from a pseudomonoradical to that of a zwitterionic one. A one-step mechanism is predicted for these polar zw-type 32CA reactions with activation enthalpies in CCl4 between 8.0 and 19.7 kcal·mol−1 at the MPWB1K (PCM)/6-311G(d,p) level of theory. The negative reaction Gibbs energies between −3.1 and −13.2 kcal·mole−1 in CCl4 suggests exergonic character, making the reactions irreversible. Analysis of the sequential changes in the bonding pattern along the reaction paths characterizes these zw-type 32CA reactions. The increase in nucleophilic character of the trimethylsilyldiazoalkanes makes these 32CA reactions more polar. Consequently, the activation enthalpies are decreased and the TSs require less energy cost. Non-covalent interactions at the TSs account for the stereoselectivity found in these 32CA reactions involving the bulky trimethylsilyl group.
Highlights
Since the last decade, trimethylsilyldiazomethane [1] has been a popular synthetic reagent owing to its commercial availability
This mild, safe, and efficient alternative has been used for the esterification of naturally occurring carboxylic acids [1,2], preparation of silylenol ethers [3], synthesis of gem-silylboronate esters [4], and ring expansion reactions [5], while one of the most important applications of trimethylsilyldiazoalkanes is the generation of functionalized pyrazolines from [3+2]
We have presented this study into six sections: (1) In Section 3.1, the Electron Localization Function
Summary
Trimethylsilyldiazomethane [1] has been a popular synthetic reagent owing to its commercial availability. This mild, safe, and efficient alternative has been used for the esterification of naturally occurring carboxylic acids [1,2], preparation of silylenol ethers [3], synthesis of gem-silylboronate esters [4], and ring expansion reactions [5], while one of the most important applications of trimethylsilyldiazoalkanes is the generation of functionalized pyrazolines from [3+2] cycloaddition. Organics2020, 1,(32CA) reactions with alkene derivatives [6,7] (Scheme 1).
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
