Diastereoselective Decarboxylation of Cyclopentene Dicarboxylic Acid Derivatives

Abstract

We investigated the decarboxylation of 2-phenylcyclopent-3-ene-1,1-dicarboxylic acid (1) and its derivatives from the ab initio calculations. The reaction pathway starting from the R-configuration of 1 has been researched, and the transition states and endiol intermediates are computationally identified based on the imaginary frequency and its normal mode. The six membered ring transition states show the concerted mechanism for the C-C bond breaking and O-H bond formation. The intermediates are converted into the (R,R)-or (S,R)-2-phenylcyclopent-3-ene carboxylic acid. It has been found that the energy difference between two reactants (R1 and R2) is small (∼1.1 kcal/mol) and is virtually the same as that between two transition states (TS1 and TS2), while the energy difference between the (R,R) and (S,R) isomers of the product is much larger (∼7.39 kcal/mol). Thus, the stereochemistry of the product can be determined from the relative stability of the products as well as that of the transition states. The trans isomer is found to be favored due to its less steric hindrance than the cis isomer, which is consistent with previous experimental observation. However, the intramolecular interactions such as hydrogen bonding and π-hydrogen interaction also play a role to a certain extent.

Catalyzed Chemical Synthesis of Unnatural Aromatic Polyhydroxyalkanoate and Aromatic–Aliphatic PHAs with Record-High Glass-Transition and Decomposition Temperatures

“…This notable diastereoselectivity can be attributed to the thermodynamically controlled formation of the trans-isomer in the equilibrium tautomerization step of decarboxylation. 62 The final oxidation to 8DL Bn occurred with retention of stereochemistry thus forming predominately meso-8DL Bn , which was confirmed by 1 H NMR and also verified by single-crystal X-ray crystallography (Scheme 1). The overall yield of meso-8DL Bn was 35% based on dimethyl succinate or 54% based on the commercial dicarboxylate intermediate.…”

“…Interestingly, unlike the aliphatic derivatives where a typical 2:1 rac / meso diastereomeric ratio was retained throughout the synthesis, the decarboxylation of a 1:1 rac / meso mixture of the benzyl β-ketoester resulted in selective formation of trans meso -dione (90%, vs 10% cis rac -diastereomer, Scheme ). This notable diastereoselectivity can be attributed to the thermodynamically controlled formation of the trans -isomer in the equilibrium tautomerization step of decarboxylation . The final oxidation to 8DL Bn occurred with retention of stereochemistry thus forming predominately meso -8DL Bn , which was confirmed by 1 H NMR and also verified by single-crystal X-ray crystallography (Scheme ).…”

Vibronic Structure of Jet-Cooled 2,6-Dimethylbenzyl Radical: Revisited

“…This has already been applied to the vibronic assignments of many benzyl-type radicals. [19][20][21] The vibronic bands observed in this study, together with the assignments, are listed in Table 1.…”

Understanding of Molecular Functions: Computational Approaches

“…We have presented only a few examples, fluorescent fluoride sensor, "on-off" molecular switch, electron transport through π-stacking, and molecular electronic device. There are number of other examples such as stereoselective organic reactions, 48 organometal catalytic reaction, 49 and crystal engineering, 50 in which this can be successfully applied. Furthermore, much more interesting phenomena of all branches of science are still a waiting reasonable explanations, and they can be supported by computational approaches.…”