Electron ionization mass spectra of phosphorus‐containing heterocycles. I. 1,4,4a,5,6,7,8,8a‐octahydro‐2H‐3,1,2‐benzoxazaphosphinine 2‐oxides

Abstract

The electron ionization mass spectra of 27 cis- and trans-annelated 1,4,4a,5,6,7,8,8a-octahydro-2H-3,1,2-benzoxazaphosphinine 2-oxides were recorded to clarify the effects of the ring heteroatom (O or N), ring annelation, the P configuration and the substituents attached to the ring or to the N and P atoms. For compounds 1-12 different alkyl radical and alkene losses and the cleavage of the P-heteroatom bonds, instead of the P-C bonds, were representative and dependent mainly on the substitution on the N and P atoms. The replacement of Ph and OPh by N(CH2CH2Cl)2 on the P atom had a dramatic influence on the fragmentation process: new fragment ions were obtained and very little M+ (1-3%) was formed. Only slight differences were found between some of the corresponding isomers, but interestingly the compounds formed clear groups on the basis of the differences in their fragmentation, depending on the ring-N and ring-P substituents.

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

“…There are practically no qualitative differences between the corresponding cis ‐ or trans ‐annelated isomers and their P epimers (Table 1), which furnish similar fragmentation patterns in electron ionization. They are even more similar than was the case with the 1,4,4a,5,6,7,8,8a‐octahydro‐2 H ‐3,1,2‐benzoxazaphosphinine 2‐oxides studied earlier 1. The main differences relate to the presence of various fragment ions which can be explained in terms of the different internal energies of the isomeric molecular ions 6.…”

“…The effects of the substituents on the ring N and P atoms, the ring fusion and the P stereochemistry on the various decompositions were of interest. Comparisons are also made with the results on the corresponding 3,1,2‐O,N,P derivatives discussed earlier 1. While the ring system in the 1,3,2‐N,N,P compounds is of pharmacological importance, as revealed by their anticancer2 and immunosuppressant3 properties, the 1,3,2‐N,N,P analogs of cyclophosphamide do not possess significant anticancer activity 4…”

“…As a continuation of our mass spectrometric studies on P‐containing heterocycles,1 the mass spectrometric behavior of 17 cis/trans ‐fused isomeric pairs of 1,2,3,4,4a,5,6,7,8,8a‐decahydro‐1,3,2‐benzodiazaphosphinine 2‐oxides (Table 1) is now reported. The effects of the substituents on the ring N and P atoms, the ring fusion and the P stereochemistry on the various decompositions were of interest.…”

6-Membered P-Heterocycles: Ring-Condensed 1,3,2-Diheterophosphorinane 2-Chalcogenides

“…The axial or equatorial preference of the P substituents can shift the N-in/N-out equilibrium in a direction such that the substituents can occupy their preferred positions in the chair conformation, but both chair forms can depopulate towards more preferable skew conformations when the P configuration is unfavourable (Scheme 13). The fragmentations of compounds 81-94 and 101-114 have been thoroughly studied by means of electron ionization MS [69,70].…”

Electron Ionization Mass Spectra of Organophosphorus Compounds. Part III: Mass Spectrometric Fragmentation of Diethyl Spiro[Pyrimidino[5,3′][1,2]Oxazole] Phosphonate, Diethyl (Oxazolo[5,4-D]Pyrimidine-4,6-Dione)Phosphonate, and Diethyl (Pyrimidino[4,5-B][1,4]Oxazine)Phosphonate Derivatives

“…[5][6][7][8][9][10] Mass spectrometry (MS) was applied to the characterization of this class of compounds using analysis of metastable ions by the collision induced dissociation technique and exact mass measurements. [11][12][13][14][15] The mass spectral fragmentation patterns under ionization of phosphorus containing isolated or fused heterocycles were studied in detail. However, to our knowledge, there is no mass spectral fragmentation studies for spiro-and fused phosphorus compounds.…”