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A Dual‐Functional Catalyst for Cascade Meerwein–Pondorf–Verley Reduction and Dehydration of 4′‐Methoxypropiophenone to Anethole
Author(s) -
Zhang Hongwei,
Lim Candy LiFen,
Zaki Muhammad,
Jaenicke Stephan,
Chuah Gaik Khuan
Publication year - 2018
Publication title -
chemsuschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.412
H-Index - 157
eISSN - 1864-564X
pISSN - 1864-5631
DOI - 10.1002/cssc.201801340
Subject(s) - anethole , chemistry , catalysis , dehydration , organic chemistry , microporous material , chromatography , biochemistry , essential oil
Anethole is an ingredient in many flavours, fragrances and pharmaceutical formulations. To reduce the dependence of its supply on natural oils, a green route for anethole synthesis was designed on the basis of Meerwein–Pondorf–Verley (MPV) reduction and dehydration of 4′‐methoxypropiophenone. The one‐pot cascade reactions were heterogeneously catalysed by dual‐functional Zr‐MSU‐3, a predominantly Lewis‐acidic catalyst with a Si/Zr ratio of 10 and pores with sizes in the range of 3.2–4.2 nm. The use of 2‐pentanol as solvent and hydrogen donor for the MPV reduction was advantageous, as its high boiling point enhances the rate of the reactions, especially the dehydration of the MPV product, 1‐(4‐methoxyphenyl)‐propan‐1‐ol. This dispenses with the need for a strong acid catalyst that could result in by‐products of acid‐catalysed reactions. Anethole yields of 91 % with a trans / cis isomer ratio of about 92:8, similar to that of natural anethole, were obtained. In comparison, microporous Zr‐beta (Si/Zr 12.5) gave lower activity owing to pore‐size constraints. Hence, through design of the reactions and catalyst, 4′‐methoxypropiophenone can be efficiently converted to anethole in a sustainable and green manner.