Synthesis of Camphor by the Oxidation of Borneol | …
X. Jones Reaction: The Oxidation of Borneol to Camphor
Ceacero-Vega, A. A.; Ballesteros, B.; Bejan, I.; Barnes, I.; Jiménez, E.; Albaladejo, J. Kinetics and Mechanisms of the Tropospheric Reactions of Menthol, Borneol, Fenchol, Camphor, and Fenchone with Hydroxyl Radicals (OH) and Chlorine Atoms (Cl). J. Phys. Chem. A 2012, 116 (16), 4097-4107. Rafiński, Z.; Kozakiewicz, A. Enantioselective Synthesis of Chromanones Bearing Quaternary Substituted Stereocenters Catalyzed by (1R)-Camphor-Derived N-Heterocyclic Carbenes. J. Org. Chem. 2015, 80 (15), 7468-7476. McLain, K. A.; Miller, K. A.; Collins, W. R. Introducing Organic Chemistry Students to Natural Product Isolation Using Steam Distillation and Liquid Phase Extraction of Thymol, Camphor, and Citral, Monoterpenes Sharing a Unified Biosynthetic Precursor. J. Chem. Educ. 2015, 92 (7), 1226-1228.
Borneol, Camphor, and Isoborneol
Inspection of a molecular model of camphor will reveal that the exo face isconsiderably more sterically hindered than the endo face, due to the presence of one ofthe methyl groups. Since "endo-attack" of borohydride avoids thissteric interaction, we might predict that it should proceed faster than exo-attack,leading to stereoselective reduction. The use of steric effects to control reactivity inthis way is termed steric approach control. The extent to which we are successfulin controlling the stereoselectivity of the reduction will be gauged by determining therelative yields of borneol and isoborneol using gas chromatography.