An Anomalous Oxidation of β‐Pinene

Abstract

The oxidation of β‐pinene with aqueous alkaline potassium periodate and catalytic amounts of potassium permanganate gave, in addition to the expected oxidation product nopinone, a β‐ketol. The structure of the latter was shown to be 1‐(2‐hydroxyisopropyl)bicyclo[3.1.0]hexan‐2‐one. The formation of this anomalous side‐product represents a new type of rearrangement of the pinane skeleton.

A New Paradigm in Oxidative Cleavage Reaction: The Use of Continuous Reactors To Enable Safe Scale Up of Ozonolysis

“…For example, high yields (95%) have been obtained using a combination of 4 equiv. NaIO 4 with a catalytic amount of KMnO 4 (20 mol%) (6). In other studies, a combination of NaIO 4 with either OsO 4 (7) or RuCl 3 (8) also furnished reasonable yields of nopinone [2].…”

Synthesis of Nopinone from β‐Pinene – A Journey Revisiting Methods for Oxidative Cleavage of C=C Bonds in Terpenoid Chemistry

“…Lactone 12 (63 %) was the major constituent, whereas ketone 11 , resulting from decarboxylation and dehydration in a sequence similar to that in 4a → 1 (Scheme ), was formed only in 1 % yield. Use of a combination of NaIO 4 and KMnO 4 in 1:0.05 molar ratio (Rudloff reagent) in aqueous K 2 CO 3 allowed for the selective formation of 11 and explained the occurrence of condensed tetrahydrofuran derivatives 12 and 13 39. In the presence of pyridine as solvent, 13 was formed in 13 % yield 38.…”

“…Additionally, the combination of 4 equiv. NaIO 4 with non‐stoichiometric amounts of KMnO 4 (20 mol‐%) in a basic aqueous environment allowed the oxidation of 2 to afford 1 in 95 % yield 39. The presence of t BuOH as co‐solvent was important, because it allows the solution of inorganic and organic substrates, decreasing transport limitations.…”