Preparation of Bis(2,4,6‐Trimethylpyridine)Iodine(I) Hexafluorophosphate and Bis(2,4,6‐Trimethylpyridine) Bromine(I) Hexafluorophosphate

Abstract

Preparation of bis(2,4,6‐trimethylpyridine)iodine(I) hexafluorophosphate and bis(2,4,6‐trimethylpyridine) bromine(I) hexafluorophosphate intermediate: Bis(2,4,6‐trimethylpyridine)silver(I) hexafluorophosphate product: bis(2,4,6‐trimethylpyridine)iodine(I) hexafluorophosphate product: bis(2,4,6‐trimethylpyridine)bromine(I) hexafluorophosphate

An Approach to Enantioselective 5‐endo Halo‐Lactonization Reactions

“…To study the enantioselective version of this reaction, we chose (-)-N-methylephedrine (19) as the chiral amine. As described above for the preparation of the iodo complexes (Scheme 1), iodobis(N-methylephedrine) hexafluoroantimonate (20) was prepared by the reaction of 2 equivalents of N-methylephedrine (19) with 1 equivalent of iodine in the presence of 1 equivalent of silver hexafluoroantimonate (Scheme 4). Like the complexes in Scheme 1, complex 20 was unstable at room temperature and was thus prepared and used at a low temperature.…”

“…With these acids, as with acid 17, only the 5-endo lactonization reactions were observed (Scheme 11). The iodolactones 52a,b were obtained from the (E) acids 50a,b by reaction with iodobis(N-methylephedrine) hexafluoroantimonate (20) in the presence of bis(N-methylephedrine)silver hexafluoroantimonate (21) and were identified by spectroscopic methods. In the two cases, the proportions of the two enantiomers were deduced from GC chromatograms.…”

“…We prepared the tetrabutylammonium carboxylate 56 to examine whether a simple ammonium salt could be involved in this kind of cyclization reaction. By reaction with iodobis(N-methylephedrine) hexafluoroantimonate (20) in the presence of the silver complex 21, we obtained the racemic iodolactone 18 (90 % yield). Similar results were obtained from the chiral ammonium salt 57 in its reaction with iodobis(collidine) hexafluorophosphonate or iodobis(N-methylephedrine) hexafluoroantimonate (21) (Scheme 12).…”

Preparation of Imino Lactones by Electrophilic Cyclization of β,γ‐Unsaturated Hydroxamates: Formation of 3‐Cyanoprop‐2‐en‐1‐ones through Fragmentation Reactions

“…Purification of products was carried out by normal-phase flash chromatography. 3-Cyclohexylidenepropanoic acid (1, 81%) [7] and bis(collidine)bromine(I) hexafluorophosphate [18] were prepared as reported previously.…”

“…: Bis(collidine)bromine(I) hexafluorophosphate [18] (0.66 mmol, 307 mg) was added to a dichloromethane solution (10 mL) of the hydroxamate 4 (127 mg, 0.6 mmol). After 2 h at room temp., the solvent was removed under vacuum.…”