A convenient method has been developed for the synthesis of diphenyl α-(dipropoxyphosphoramido) alkyl- phosphonates under mild conditions, namely the reaction of dipropyl phosphoramidate (1) with a para-(un)substituted benzaldehyde or cyclicketone (2) and triphenyl phosphite (3) by a one-pot procedure with the aid of acetyl chloride.

N-(1,3,2-Dioxaphosphorinan-2-ylmethyl) thiophosphoramidates were synthesized and determined by NMR spectra and positive ion electrospray ionization mass spectrometry (ESI-MS) in conjunction with tandem mass spectrometry (MS/MS). The fragmentation pathways were investigated. The results show that these characteristic ions in ESI mass spectra are useful in the structural determination of N-(1, 3, 2-dioxaphosphorinan-2-ylmethyl)- thiophosphoramidates.

A study on the synthesis of the novel cyclic α-aminophosphonates and 2-alkoxy-2- oxo-1, 4, 2-oxazaphosphinanes 4a–r has been carried out. The title compounds were obtained in good yields by one-pot procedure using o-aminophenol, alkyl dichlorophosphinite, and ketones or benzaldehyde. One of their geometric stereoisomers was isolated and characterized. Configurations of 4k and one isomer of 4r have been established by X-ray diffraction analysis. The synthetic methods provide an easy access to the organophosphorus heterocycles with the ring system mentioned above. The abnormal chemical shifts of alkyl-substitute protons in 1H NMR spectra were given reasonable explanation.

A study on the synthesis of the novel N-(cyclic phosphonate)-substituted phosphoramidothioates, i.e., O, O-diethyl N-[(trans-4-aryl-5, 5-dimethyl-2-oxido-2λ5-1, 3, 2-dioxaphosphorinan-2-yl) methyl] phosphoramidothioates 4a–1, from O, O-diethyl phosphoramidothioate (1), a benzaldehyde or ketone 2, and a 1, 3, 2-dioxaphosphorinane 2-oxide 3 was carried out (Scheme 1 and Table 1). Some of their stereoisomers were isolated, and their structure was established. The presence of acetyl chloride was essential for this reaction and accelerated the process of intramolecular dehydration of intermediate 5 forming the corresponding Schiff base 7 (Scheme 2).

Base-promoted (KOH or MeONa in MeOH, or NaH in THF) cycloisomerisation of partially benzylated, 1-substituted (R=Ph-C≡C, pyridin-2-yl, or Br) ald-1-ynitols leads to (Z)-configured five-, six-, and seven-membered exo-glycals. The reactivity of the ald-1-ynitols depends upon their configuration. The ald-1-ynitols were derived from 2,3,5-tri-O-benzyl-D-ribofuranose 1, and the corresponding, partially O-benzylated galactose, glucose, and mannose hemiacetals by ethynylation. The hex-1-ynitol 2 derived from 1 (61%) was transformed via the 1-phenylbutα-1,3-diyne 3 and the 1-(pyridin-2-yl)acetylene 5 into the five-membered exo-glycals 4 and 6 (in 66 and 72% yields, resp., from 2). The analoguous ethynylation of 2,3,4,6-tetra-O-benzyl-D-galactose 8 was accompanied by elimination of one benzyloxy (BnO) group to the hept-3-en-1-ynitol 9 (71%), which was trans- formed into the non-5-ene-1,3-diynitol 10 and further into the six-membered exo-glycal 11 (50% from 9). Addition of Me3SiC≡CH to the galactose 8 and to the gluco- and manno-analogues 16 and 24 gave epimeric mixtures of the silylated oct-1-ynitols (86% of 12L/12D 45 : 55, 94% of 17L/17D 7 :3, and 86% of 25L/25D 55 :45), which were separated by flash chromatography, and individually transformed into the corresponding 1-bromooct-1-ynitols. Upon treatment with NaH in THF, only the minor epimers 13L, 18D, and 26D cyclised readily to form the seven-membered hydroxy exo-glycals. They were acetylated to the more stable monoacetates 14L, 23D, and 28D (82–89% overall yield). Under the same conditions, the epimers 13D, 18L, and 26L decomposed within 12 h mostly to polar products. The difference of reactivity was rationalised by analysing the consequences of an intramolecular C(3)O-H···—OC(7) H-bond of the intermediate alkoxides on the orientation of —O-C(7) of 13L, 18D, and 26D and its proximity to the ethynyl group.