Extended Data Fig. 8: The calculated reaction energy profile shows the plausible reactions of 2 toward 5. | Nature Chemistry

Extended Data Fig. 8: The calculated reaction energy profile shows the plausible reactions of 2 toward 5.

From: An enzymatic dual-oxa Diels–Alder reaction constructs the oxygen-bridged tricyclic acetal unit of (–)-anthrabenzoxocinone

Extended Data Fig. 8

The Gibbs free energies, given in kcal mol−1, were used to quantify the thermodynamics of these processes at the B3LYP(D3)/def2-TZVP(SMD) level of theory. The energy profile of the two potential dehydration pathways involved in the conversion of 2 to enantiomeric intermediates 3. Following this, besides undergoing oxo-Diels-Alder cyclization to yield the products (−)-ABX and (+)-ABX, the compound 3 can undergo disrotatory oxa-6π electrocyclization to form less stable compounds 5 after hydrogen abstraction from the acetyl methylene substituent. Alternatively, compound 3 form an enolate ion under basic condition and go 1,4-Michael addition forming the anionic form of compound 5 (blue dotted box).

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