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Rhodium catalyzed hydroformylation of monoterpenes containing a sterically encumbered trisubstituted endocyclic double bond under mild conditions

Paper ID Volume ID Publish Year Pages File Format Full-Text
43532 45975 2007 8 PDF Available
Title
Rhodium catalyzed hydroformylation of monoterpenes containing a sterically encumbered trisubstituted endocyclic double bond under mild conditions
Abstract

The rhodium catalyzed hydroformylation of endocyclic monoterpenes, that is, 2-carene (1), 3-carene (2), and α-pinene (3), in the presence of PPh3 or various diphosphines and phosphites has been studied. The unmodified Rh catalyst promotes an intense isomerization of both carenes whose hydroformylation occurs rather slowly, and results in a complex mixture of aldehydes and alcohols. The addition of PPh3, diphosphines or P(OPh)3 in a P/Rh ratio as high as 20, efficiently prevents the isomerization, but the activity for hydroformylation is drastically reduced. On the other hand, the use of a bulky P(O-o-tBuPh)3 ligand both reduces the isomerization, and significantly increases the hydroformylation rate. All three sterically crowded olefins 1–3 have been efficiently hydroformylated under relatively mild reaction conditions (80–100 °C, 40–80 atm) to a main aldehyde (2-formylcarane, 4-formylcarane, and 3-formylpinene, respectively) with good chemo- and regioselectivity, and almost 100% stereoselectivity for the trans isomers.

Graphical abstractThe rhodium catalyzed hydroformylation 2-carene (1), 3-carene (2), and α-pinene (3), in the presence of PPh3 or various diphosphines and phosphites has been studied. The use of a bulky P(O-o-tBuPh)3 ligand both improves the selectivity, and increases significantly the hydroformylation rate under relatively mild reaction conditions (80–100 °C, 40–80 atm).Figure optionsDownload full-size imageDownload as PowerPoint slide

Keywords
2-Carene; 3-Carene; α-Pinene; Hydroformylation; Rhodium catalyst; Bulky phosphite
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Rhodium catalyzed hydroformylation of monoterpenes containing a sterically encumbered trisubstituted endocyclic double bond under mild conditions
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Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis A: General - Volume 326, Issue 2, 15 July 2007, Pages 219–226
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Catalysis
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Don't Miss Today's Special Offer
Price was $35.95
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Price after discount Only $4.95
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