Glycol Fission in Rigid Systems. I. The Camphane-2,3-diols1

Kinetically controlled optical resolution of racemic norbornene aldehyde derivatives

A new method for obtaining optically pure 5-norbornene 2-endo-aldehyde derivatives was developed. The reaction of a diastereomeric mixture of the ene acetals 2 and 2', derived from racemic norbornene aldehydes (+/-)-1 and chiral nonracemic (S,S)-hydrobenzoin 7, with NBS (0.5-0.6 eq.) in the presence of H(2)O proceeded in a kinetically controlled manner to give the optically pure hydroxy aldehydes 3 along with the intact ene acetals 2'. Both compounds 3 and 2' were converted into the optically pure norbornene aldehydes 1 and ent-1, respectively. This method opens the way to produce various types of 5-norbornene 2-endo-aldehydes with 3-exo- or 3-endo-substituents in optically pure forms.

Monoterpenoids from the seeds of Heracleum candolleanum

The isolation and NMR spectra of 2-exo,3-endo-camphanediol (1) and 2-pinene-4,10-diol (2) from the seeds of Heracleum candolleanum are reported.

COUPLING CONSTANTS IN RIGID FIVE-MEMBERED RINGS: N.M.R. SPECTRA OF THE CAMPHANE-2,3-DIOLS

The proton nuclear magnetic resonance (N.M.R.) spectra of the four diastereoisomers of camphane-2,3-diol are reported. The coupling constants between the 2-, 3-, and 4-protons agree with the values predicted by Karplus for ethane derivatives. In particular, the cis (0° dihedral angle) coupling constants (7.7 and 8.9 c.p.s.) are much larger than the trans (120° dihedral angle) coupling constants (2.2 and 2.3 c.p.s.). Unexpected 1,3-coupling between exo-hydrogen atoms occurs in some of the compounds studied.

HYDROGENOLYSIS OF CARBOHYDRATES: IX. FORMATION OF 2,6-ANHYDRO-β-D-FRUCTOFURANOSE AND ETHYL α- AND β-D-FRUCTOFURANOSIDE FROM SUCROSE

A compound formed during the hydrogenolysis of sucrose in ethanol or dioxane at 180 °C, in the presence of copper chromium oxide catalyst, has been characterized as 2,6-anhydro-β-D-fructofuranose (2,5-anhydro-α-D-fructopyranose), a new type of anhydro-ketose. Ethyl α- and β-D-fructofuranosides are also produced when the hydrogenolysis reaction is carried out in ethanol, and various derivatives of these anomeric ketosides have been prepared.