Extended Data Fig. 5: Proposed SN1 and SN2 model of Abx(−)F and the DFT calculation. | Nature Chemistry

Extended Data Fig. 5: Proposed SN1 and SN2 model of Abx(−)F and the DFT calculation.

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

Extended Data Fig. 5

a, Proposed reaction diagram of SN1 and SN2. b, The high strain in the 8-membered ring prevents the C24 hydroxyl group from approaching the C8 atom. (i) The ground state of the 8-membered ring intermediate upon hemiketalization, in which the C24 hydroxyl group points outward; (ii) The local minimal with the shortest C8–O(C24) distance, the conformation of which is higher by 8.3 kcal mol−1 at the B3LYP(D3)/def2tzvp (SMD) level of theory. c, The energy will further increase to as high as 83.1 kcal mol−1 when the distance decreases to 1.8 Å. Thus, an SN2 mechanism is unlikely to take place. Moreover, there is no specific reason to form high-energy carbon cation species through an SN1 mechanism as well.

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