Mass spectrometric determination of the configuration of 2‐methyl‐and 1,2‐dimethyl‐4‐vinyl‐ethinyl(n‐butyl)‐4‐hydroxyperhydroquinolines

Abstract

The configuration at C-2 and C-4 in the molecules of 2-methyl-and 1,2-dimethyl-4-vinylethinyl(n-butyl)-4-hydroxyperhydroquinolines was determined by mass spectrometry The principal conclusions concerning the stereochemistry were made on the basis of differences in the values of the I[H-151+/I[xl+., IIH-l,~+/I~ar~+.. I[l-n31+/I[ar~+. and IIM-,,~+/I[y~+. ratios in the mass spectra of the epimeric vinylethinylic alcohols, and of the I~x -l s~+ / I~x l + . and I~M-s,l+/I~arl+. ratios in the case of the n-butylic alcohols CONTINUING work on the mass spectrometric determination of the configuration of the 4-substituted 2-methyl-4-hydro~yperhydroquinolines,~ we studied the mass spectra of the 2-and 4-epimers of 1,2-dimethyl-(IIIa to IIIc) and 2-methyl-4-vinylethinyl-4-

Electron ionization mass spectra of phosphorus‐containing heterocycles. II. 1,2,3,4,4a,5,6,7,8,8a‐decahydro‐1,3,2‐benzodiazaphosphinine 2‐oxides

“…(6–9%) and [M–C 7 H 9 ] + (5–7%) as the most abundant ions. Compounds 3 and 4 gave [M–C 6 H 11 ] + (8–11%), [M–C 7 H 11 ] + (6–7%) (this is comparable with the situation for decahydroquinolines,8–10 some other heterocyclic compounds studied earlier,17 and 1,4,4a,5,6,7,8,8a‐2 H ‐3,1,2‐benzoxazaphosphinine 2‐oxides1 when R 1 = CH 3 and R 2 = Ph), [M–NH 3 ] + . (7–13%), and [M–CH 3 NH] + (5–6%) as the most abundant ions.…”

“…The respective ions are stabilized by conjugation (Scheme ), which in this case also makes formation of [M–C 4 H 9 ] + favored although it was of minor importance in the corresponding 3,1,2‐O,N,P derivatives 1. This type of fragmentation is common for bicyclic N heterocycles8–12 and it has also been observed for some perhydro‐1,3‐oxazine derivatives 13, 14…”

Stereospecific Ion—molecule Reactions in the Trans-Decahydro-4-Hydroxyquinoline Series upon Chemical Ionization

“…Their structure and stereochemistry has been proved earlier. 9,10 Owing to their high volatility, the samples were introduced into the ion source of the mass spectrometer through the gas chromatographic inlet.…”

“…This is clearly manifested by the stereospecificity of organometallic reactions (for example, the Grignard reaction) with C-2 stereoisomeric 2-methyltrans-decahydro-4-oxoquinolines. 10 Thus, in the case of a ketone with an axial 2-CH 3 group, the attack of a bulky reagent (R 2 MgX, where R 2 is alkyl) in the axial area is strongly hindered and only one stereoisomer is formed in the course of the reaction (Scheme 5).…”

“…To solve the problem, the application of electron ionization mass spectrometry was earlier suggested. 9,10 It was shown that the molecular ion of the alcohols with saturated (alkyl) substituents at C-4 expels the alkyl radical much more readily when it has an axial, rather than equatorial, orientation. It is not possible to use this method for the determination of the configuration of the compounds with unsaturated groups at C-4 because such substituents are not eliminated from M + .…”