Efficient Isomerization of alpha-Pinene Oxide to Campholenic Aldehyde Promoted by a Mixed-Ring Analogue of Molybdenocene

authors	Bruno, SM; Valente, AA; Pillinger, M; Arnelse, J; Romao, CC; Goncalves, IS
nationality	International
journal	ACS SUSTAINABLE CHEMISTRY & ENGINEERING
author keywords	Renewable resources; Terpenes; Rearrangement; Homogeneous catalysis; Molybdenum; Metallocenes; Lewis acids; Ionic liquids
keywords	IONIC LIQUIDS; REARRANGEMENT; CATALYSTS; ACID; EPOXIDATION; SOLVENTS
abstract	The Mo-IV complex [(eta(5)-indenyl)(eta(5)-cyclopentadienyl)Mo(MeCN)(2)](BF4)(2) (1) has been used to promote two acid-catalyzed epoxide ring-opening reactions under ambient conditions. The alcoholysis of styrene oxide in neat ethanol gave 2-ethoxy-2-phenylethanol in quantitative yield within 10 min. The use of an ionic liquid (IL) as a cosolvent benefitted catalyst solubility and recycling while not impairing catalytic performance. Complex 1 in 1,2-dichloroethane was effective for the isomerization of alpha-pinene oxide to campholenic aldehyde (CPA), leading to 87% yield at 1 h of reaction. The same yield could be achieved within 1 min by using the IL [Choline][NTf2] as a solvent. CPA yields at 1 min reached near-quantitative values (98%) upon recycling of the catalyst/IL mixture, demonstrating an unparalleled combination of activity, selectivity and recyclability for this commercially important reaction. Considering the catalytic features of the 1/IL system, a CPA process flow diagram is proposed and compared to patented technology.
publisher	AMER CHEMICAL SOC
issn	2168-0485
year published	2019
volume	7
issue	16
beginning page	13639
ending page	13645
digital object identifier (doi)	10.1021/acssuschemeng.9b03087
web of science category	Chemistry, Multidisciplinary; Green & Sustainable Science & Technology; Engineering, Chemical
subject category	Chemistry; Science & Technology - Other Topics; Engineering
unique article identifier	WOS:000482173100005