Protonated cyclopropanes in α-aminoketone deamination

Abstract

. Can. J. Chem. 59,2096Chem. 59, (1981. Deamination of 2-amino-4,4-dideuterio-6,6-dimethylcyclohexanone, 2-exo-amino-and 2-endo-amino-norbornane-3-one, 2-diazonorbornan-3-one, 2-exo-amino-5,6-exo-dideuterionorbornan-3-one and the corresponding 5,6-endo-dideuterio isomer has been studied. The nature of the products, the deuterium location in them, and the high retention of steric identity in the carbocations are interpreted in terms of o-bond participation leading to corner-and edge-protonated cyclopropanes as reaction intermediates. Results with other destabilized carbocations are correlated.OLIVER E. EDWARDS, JOHN DIXON, JOHN W. ELDER, RALPH J. KOLT et MAURICE LESAGE. Can. J. Chem. 59,2096 (1981. On a etudik la desamination de I'amino-2 dideutero-4,4 dimethyl-6,6 cyclohexanone, des amino-2 exo et amino-2 endo norbornanones-3, de la diaza-2 norbornanone-3, de l'amino-2-exo dideutero-5,6-exo norbornanone-3, ainsi que de son isomkre dideutero-5,6-endo. On interprete la nature des produits, la position des deuterium qu'ils contiennent ainsi que le taux eleve de retention [Traduit par le journal]

A novel method for stereoselective glucuronidation

“…a 4:1 mixture of a/ß epimers. (7) I support a mechanism which is essentially an acid-catalyzed etherification. The ratio of the epimeric products (a and ß anomers) produced (as estimated by NMR) depends largely on the aglycon used and reflects the net effect of two counteracting properties: (a) aglycon nucleophilicity and (b) its tendency to form a stabilized carbocation resulting from a formal loss of an -OH group.…”

Novel reactions of lycoctonine analogs: unusual pyrolysis of C4–COOH and hydrogenolysis of N–C6 bond

“…Its ESIMS showed a quasimolecular ion peak at m/z 388 [Mþ1] þ and its NMR spectroscopic patterns are quite different from those of its starting material 2. The NMR ( 1 H, 13 (Fig. 1), which indicated that the vicinal glycol moiety in 2 had undergone Pinacol rearrangement.…”

“…Melting points were determined on a Kofler block (uncorrected); optical rotations were measured in a 1.0 dm cell with a PE-314 polarimeter at 20AE1 C; IR spectra were recorded on a Nicolet 200 SXV spectrometer; MS spectra were obtained with Finnigan LCQ DECA mass spectrometer; HRMS spectra were obtained with a Bruker BioTOFQ mass spectrometer; 1 H and 13 , and the mixture was stirred at 0 C for 1.5 h prior to be quenched with saturated Na 2 SO 3 . The organic layer was separated and the aqueous layer was re-extracted with CH 2 Cl 2 (15 mlÂ2).…”

Lanostane-to-cucurbitane transformation

“…This was prepared by the action of acid on bryodulcosigcnin (16) from Brqo~~icr crlhcr (20). After crystallization from acctone-liexanc it had mp 157-158°C.…”

“…Final proof of structure of A and B came from interrelation with the cucurbitacins bryodulcosigenin 16 (20) and bryogenin 17 ( 19) from Bryorzia alba (20) .' The 24-carbony l of bryogenin was removed in two ways, by cyanoborohydride reduction (21) of its 24-tosylhydrazone (18) or by Wolff-Kishner reduction of the 24-semicarbazone.…”