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Synthesis of Fragrance Compounds from Biorenewables: Tandem Hydroformylation–Acetalization of Bicyclic Monoterpenes
Author(s) -
de Freitas Marina C.,
Vieira Camila G.,
dos Santos Eduardo N.,
Gusevskaya Elena V.
Publication year - 2013
Publication title -
chemcatchem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.497
H-Index - 106
eISSN - 1867-3899
pISSN - 1867-3880
DOI - 10.1002/cctc.201200948
Subject(s) - chemistry , pinene , hydroformylation , aldehyde , terpene , organic chemistry , reactivity (psychology) , limonene , bicyclic molecule , catalysis , solvent , rhodium , essential oil , chromatography , medicine , alternative medicine , pathology
The Rhodium‐catalyzed tandem hydroformylation–acetalization of the terpenes 3‐carene, 2‐carene, α‐pinene, and β‐pinene was studied in ethanol solutions in the presence of PPh 3 or tris( O ‐ tert ‐butylphenyl)phosphate, P(O‐ o ‐ t BuPh) 3 , ligands. All these terpenes are constituents of turpentine oils obtained commercially from coniferous trees. β‐Pinene gave the corresponding aldehyde and acetal in excellent combined yields in both systems. 3‐Carene, 2‐carene, and α‐pinene, which contain sterically encumbered endocyclic double bonds, showed an extremely low reactivity with PPh 3 . The use of P(O‐ o ‐ t BuPh) 3 not only accelerated the hydroformylation of all four substrates remarkably but also increased the acetalization activity of the catalyst. In the Rh/P(O‐ o ‐ t BuPh) 3 system, various fragrance acetals and aldehydes were obtained from these renewable substrates in nearly quantitative combined yields. The process was performed under mild conditions, in environmentally friendly ethanol as a solvent, and in the absence of acid cocatalysts.