1,4,2‐Diazaphospholothiazoles and ‐pyridines by a Hantzsch‐Type Condensation Using Chloromethyldichlorophosphane

Abstract

Regioselectivity / 31P-, lH-, 13C-NMR spectraThe [3 + 21 cyclocondensation of 2-amino-1,3-thiazoline, 2-aminopyridines, 2-and 4-aminopyrimidines, 2-aminopyrazine, and 2-aminoquinoline with chloromethyldichlorophos- [',*]. These syntheses often parallel those of azoles: When carboxylic acid derivatives are used for condensation to yield azoles, phosphorus trihalides or trisamides take their part in azaphosphole syntheses. When acetylenes are employed in the synthesis of azoles involving cycloaddition, phosphaalkynes are used instead for azaphospholes. A further route to azaphospholes by a condensation reaction may be understood as a parallel of the Hantzsch thiazole synthesis, with the part of the ahaloketone played by chloromethyldichlorophosphane. Starting from thioamides, we thus obtained 1,3,4-thiazaphospholes and starting from amidines, we obtained 1,4,2-diazaphospholes. Only this route does give access to representatives containing an unsubstituted carbon ring member adjacent to phosphorus (i.e. in the 5-or 3-position)r31. The present paper describes the synthesis of anellated 1,4,2-diazaphospholes starting from heterocycles containing an amidine system, i.e. 2-aminopyridines and 2-amino-l,3-thiazoles, and in one case a 2-aminothiazoline. SynthesesThe condensation of equimolar amounts of 2-amino-l,3-thiazoline with chloromethyldichlorophosphane in the presence of a threefold molar amount of triethylamine in acetonitrile proceeds regiospecifically to give 5,6-dihydro

New anellated 4H-1,4,2-diazaphospholes

“…This is in contrast to the analogous cyclocondensation with the unsubstituted 2-amino-1,3-thiazole, where a 7 : 1 mixture of the 1H-and 4H-regioisomers is formed with the 1H-isomer being the major product. 13 The 4+1 cyclocondensation of the cycloimmonium salts 3a-c and 4…”

“…The 31 P NMR and selected 13 C NMR data of 2a, 5a-c and 6 are summarized in Table 1 Scheme 2 Synthesis of the 1,4,2-diazaphospoles 5a-c and 6. show a remarkable dependency on the solvent used. The change from CDCl 3 to MeCN causes a high field shift of 1.6-13.6 ppm.…”

Sulfur and selenium derivatives of 2-phosphaindolizines

“…This reaction can be extended to other 1,3,2,4-diselenadiphosphetane-2,4-diselenides 4 as well. In place of the phosphaindolizine 1a, the 1-aza-2-phosphaindolizine 8 [16] can be used to give the corresponding diselenophosphinates 9a,b. As expected, the reaction is influenced by the nucleophilicity of the phosphaindolizine as well as by the electrophilicity of the phosphorus atoms in the diselenides 4.…”

2-phosphaindolizines

“…The loss of CO generates an C 8 H 7 PN ion having the basic skeleton of 2-phosphaindolizine. Further fragmentation proceeds in close analogy to the related nitrogen heterocycles, with [21] or without [10] the presence of phosphorus. The loss of HCN from species A, typical of 1,3-azaphospholes [22], gives the ion at m/z 121, which may lose either HCP or acetylene.…”