Yan Zhankai, Liu Zhaojie^#, Chen Weibing^#
(Department of Chemistry and Environmental Engineering, Yangtze University, Jingzhou, 434025; ^# Institute of Organic synthesis, Central China Normal University, Wuhan, 430070)

Abstract The thermal rearrangement of O-allyl thionophosphates to provide S-allyl thiolophosphates was studied. The tests showed that by SiO₂ O-allyl thionophosphates was heated under nitrogen atmosphere at 110 ^oC for 1.5 hrs, were easily converted to its thiol isomer in quantitative yields_. According to this synthetic method, the twelve new compounds were synthesized and identified by IR, ¹H NMR, ³¹P NMR and elemental analysis.
Keywords thiolophosphate; synthesis; thermal rearrangement

It is an effective preparation method of allyl thiolophosphates by the rearrangement of allyl thionophosphates to provide its thiol isomers. In the early years, Pudovik^[1] reported the thermal rearrangement of allyl phosphorothionates, in acetonitrile or xylene, the reaction was very slow and in some cases gave only low conversion. Yamada^[2] first reported palladium catalyzed thiono-thiolo rearrangement of allyl thionophosphates, they found that in the absence of the catalyst, the following reaction did not occur even after prolonged reaction time. In this work, we have found that by SiO₂ O-allyl thionophosphates 1 could easily converted to its thiol isomers 2 in quantitative yields_.

    The analysis of the reaction product by TLC indicated that only one new spot was formed. As it was confirmed by ¹H-NMR, ³¹P-NMR, IR and element analysis, the new spot indicated allyl thiolophosphates 2^[3].
    To search for the better temperature condition, we chose the starting material 1 to be heated for 2 hours at 90 ^oC, 100 oC, 110 ^oC, 120 ^oC, 130 ^oC, respectively. The results are summarized in Table 1. The results showed that the yield was higher at 110 ^oC.

Table 1 the effect of temperature in yield

    We chose 110 ^oC and heated the starting material 1 for 0.5 h, 1.0 h, 1.5 h, 2.0 h, 2.5 h, 3.0 h, respectively. The results are summarized in Table 2. The results showed that the reaction come to an end in 1.5 h.

Table 2 The effect of time in yield

    Then by choosing 110 ^oC and fixing the reaction time 1.5 h, the reaction was investigated by changing substituents on aryl ring, and the results are summarized in Table 3.

Table 3 Thermal thiono-thiolo rearrangement of allyl thionophosphates

    Through the yield of products (2a-2l) in Table 3, it revealed that the rate of reaction is generally fast and quantitative, independent on the substitution pattern of aryl group.
    The general procedure is as follows: the mixture of 1 (0.01 mol) and SiO₂ (20 g) was heated under nitrogen atmosphere at 110 ^oC for 1.5 hrs, poured into ether, filtrated SiO₂. After evaporation of ether and purification of the residue by TLC (silica gel, CH₃CO₂C₂H₅ -petroleum ether), pure 2 as a viscous yellow liquid was obtained.
    This is the first report on the thermal [3, 3]-sigmatopic type rearrangement of O-allyl thionophosphates on SiO₂. The full details of the reaction will be published later on.
   
Acknowledgement We are grateful to the Hubei Natural Science Foundation for financial support.

REFERENCES AND NOTES
[1] Pudovik A N, Aladzheva I M Zh. Obshch. Khim., 1960, 30, 2617.
[2] (a) Tamaru Y, Yoshida Z  I, Yamada Y et al. J. Org. Chem., 1983, 48, 1293.
(b) Yamada Y, Suzudamo G, Yoshioka H et al. Tetrahedron Letter., 1984, 25, 3599.
[3] All new compounds (2a~2l) exhibit IR, 1H-NMR, 31P-NMR spectra and element analysis in agreement with the structure indicated. As examples, we report herein the analytical data of 2d, 2f, 2j, 2l.
2d: ¹H NMR ( CDCl₃, 200MHz ): d 3.57 (q, J = 5 Hz, 2H ), 3.94 ( d, J = 7 Hz, 3H ), 5.13-5.96 ( m, 3H ), 7.20-7.56 ( m, 4H ); ³¹P NMR (CDCl₃ ): d 26.744; IR ( cm^-1 ): 1638, 1578, 1475, 1407, 1272, 1099, 1033; Anal . calcd for C₁₀H₁₁Cl₂O₃PS: C 38.36, H 3.54, Cl 22.64; found C 38.41, H 3.56, Cl 22.62.
2f: ¹H NMR ( CDCl₃, 200MHz ): d 1.17 ( s, 9H ), 3.52 (q, J = 5 Hz, 2H ), 3.87 ( d, J = 7 Hz, 3H ), 5.13-5.84 ( m, 3H ), 7.16-7.34 ( AA'BB', J = 9 Hz, 4H ); ³¹P NMR (CDCl₃ ): δ 26.262; IR ( cm^-1 ): 1638, 1462, 1407, 1211, 1109, 1013; Anal . calcd for C₁₅H₂₃O₃PS: C 57.31, H 7.37; found C 57.30, H 7.35.
2j: ¹H NMR ( CDCl₃, 200MHz ): d 1.42 ( t, 3H ), 3.57 (q, J = 5 Hz, 2H ), 4.29-4.52 ( m, 2H ), 5.11-5.96 ( m, 3H ), 7.18-7.52 ( m, 4H ); ³¹P NMR (CDCl₃ ): d 24.903; IR ( cm^-1 ): 1638, 1581, 1451, 1253, 1099, 1056; Anal . calcd for C₁₁H₁₃Cl₂O₃PS: C 40.38, H 4.01, Cl 21.67; found C 40.39, H 4.04, Cl 21.66.
2l: ¹H NMR ( CDCl₃, 200MHz ): d 1.30( s, 9H ), 1.40 ( t, 3H ), 3.52 (q, J = 5 Hz, 2H ), 4.14-4.36 ( m, 2H ), 5.09-5.96 ( m, 3H ), 7.15-7.34 ( AA'BB', J = 9 Hz, 4H ); ³¹P NMR (CDCl₃ ): d 24.410; IR ( cm^-1 ): 1637, 1509, 1476, 1464, 1210, 1033, 1014; Anal . calcd for C₁₆H₂₅O₃PS: C 58.52, H 7.67; found C 58.57, H 7.68.

S-烯丙基硫逐磷酸酯在SiO₂上的硫逐-硫赶热重排
严赞开，刘钊杰^#，陈卫兵^#
(长江大学化学与环境工程学院，荆州 434025; ^#华中师范大学有机合成研究所，武汉 430070)
摘要 本文探讨了O-烯丙基硫逐磷酸酯热重排制备S-烯丙基硫赶磷酸酯的反应条件。结果表明: O-烯丙基硫逐磷酸酯与SiO₂混匀, 在氮气保护下, 置于110 ℃保温1.5 h, 反应可定量地完成。运用这一合成方法制备了12个不对称结构的新型硫赶磷酸酯, 所有的化合物均经IR、¹H NMR、³¹P NMR及元素分析表征。
关键词 硫赶磷酸酯; 合成; 热重排

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