Phosphorylation of Imidazo[2,1-b]thiazoles with Phosphorus(III) Halides in the Presence of Bases 655
mixture was heated under reflux for 6–7 h. The
product precipitated on cooling was filtered and
crystallized.
Synthesis of Aryliminophosphoranes 16
To a solution of aminophosphine 8–10 (2 mmol) in
toluene (30 mL) was added aryl azide (2 mmol) and
the mixture was heated under reflux until the evolu-
tion of nitrogen ceased (1–2 h). After removal of the
solvent, the residue was triturated with diethyl ether,
to induce solidification, and recrystallized.
Synthesis of Imidazo[2,1-b]thiazolium
Tetrafluoroborates 21
To a stirred solution of 4 or 8–10 (2 mmol) in
dichloroethane (30 mL) was added dropwise, at
−30◦C, solution of thriethyloxonium tetrafluorobo-
rate (2 mmol) in the same (20 mL). The reaction
mixture was stirred at room temperature for 3 h, af-
ter which the solvent was evaporated. The residue
was washed with diethyl ether until it solidified and
then dried in vacuo. Product 21b was purified by
recrystallization.
Synthesis of Phosphine Oxides 17
The corresponding chlorophosphonium chloride 14
(5 mmol) was dissolved in dichloromethane (10 mL)
and shaken with a saturated aqueous solution of
sodium carbonate. The organic layer was separated,
washed with water, dried over anhydrous sodium
sulfate, and evaporated. The residue was held in
vacuo (oily) or recrystallized (solid).
Synthesis of Imidazo[2,1-b]thiazolium
Iodides 22
Synthesis of Iminophosphorane 18
A solution of aminophosphonium chloride 15b
(5 mmol) in dichloromethane (50 mL) was shaken
with 10% aq. NaOH (30 mL) in a separatory funnel.
The organic layer was separated, dried (Na2SO4) and
evaporated. The oily product was held in vacuo.
A mixture of corresponding substrate 13a or 16a
(5 mmol) and methyl iodide (7 mmol) in benzene
(20 mL) was heated under reflux for 10–16 h. The
product precipitated after cooling was filtered and
crystallized.
Synthesis of Phosphonium Salts 19
REFERENCES
To a solution of phosphine 4 or 8–10 (1 mmol) in
benzene (30 mL) was added methyl iodide (1 mmol)
and the reaction mixture was heated under reflux
for 4–5 h. The precipitated product was filtered and
crystallized.
[1] Tolmachev, A. A.; Yurchenko, A. A.; Merculov, A.
S.; Semenova, M. G.; Zarudnitskii, E. V.; Ivanov,
V. V.; Pinchuk, A. M. Heteroatom Chem 1999, 7,
585–597.
[2] Komarov, I. V.; Kornilov, M. Yu.; Turov, A. V.;
Tolmachev, A. A.; Yurchenko, A. A.; Rusanov,
E. V.; Chernega, A. N. Tetrahedron 1995, 51,
12417–12424.
Synthesis of Compound 20
[3] Tolmachev, A. A.; Yurchenko, A. A.; Kozlov, E. S.;
Merkulov, A. S.; Semenova, M. G.; Pinchuk, A. M.
Heteroatom Chem 1995, 6, 419–432.
To a solution 8–10 (1 mmol) in acetonitrile (30
mL) was added methyl iodide (3 mmol) and the