NMR assignments for some 2‐substituted 2,6,6‐trimethyl‐7‐oxabicyclo[3.2.1]octanes (dihydropinols)

Abstract

1H and 13C NMR assignments for five 2‐substituted dihydropinols are reported.

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“…[36] Distillation onto a cold finger (bath 85°C, 0.1 Torr) gave compound (24) H and 13 C NMR spectra were consistent with the literature. [37] 2,2-Dimethyl-1,3-dioxan-5-one (25) was prepared from compound (24) with sodium periodate in potassium dihydrogen phosphate buffer (0.1 M) by the literature [36] method.…”

“…Bromination of the acetonide (16) can then occur rapidly to give compound (17) Compound (15), like 2α-bromocineole (19), is unstable in polar solvents due to the facile participation of the cineole ether oxygen in the S N 1 cleavage of the C2-Br bond. [17,24] This participation greatly hinders S N 2 attack at the back of the C2 bromine, and the model compound (19) was completely unchanged [gas chromatography (GC) analysis] after reflux with lithium aluminium hydride in tetrahydrofuran, or after reflux (5 days) with Superhydride.…”