作者:Christine A. Caputo、Jacquelyn T. Price、Michael C. Jennings、Robert McDonald、Nathan D. Jones
DOI:10.1039/b801684d
日期:——
A series of trifluoromethanesulfonate (OTf) salts of N-heterocyclic phospheniums (NHP) bearing phenyl (1a), para-methoxyphenyl (1b), 2,6-diisopropylphenyl (1c) and mesityl (1d) substituents is reported. The compounds 1b–d are made by a modification to a literature procedure that improves the overall yields for 1c and 1d by 15 and 23%, respectively. Two unwanted side-products in the synthesis of 1d, the diammonium salt, [(2,6-iPr-C6H3)N(H)2CH2CH2N(H)2(2,6-iPr-C6H3)]Cl2 (4) and the bisphosphine (2,6-iPr-C6H3)N(PCl2)CH2CH2N(PCl2)(2,6-iPr-C6H3) (5), are crystallographically characterized, as is the intermediate cyclic chlorophosphine, C1PN(4-OMe-C6H4)CH2CH2N(4-OMe-C6H4) (3b). The phenyl-substituted NHP 1a is fully characterized, including by X-ray crystallography, for the first time; this compound contains a short P–O contact of 2.1850(14) Å. Cycloaddition reactions of 1a–d with 2,3-dimethyl-1,3-butadiene give the expected spirocyclic phospholeniums, 7,8-dimethyl-1,4-diaryl-1,4-diaza-5-phopshoniaspiro[4.4]non-7-ene, as their OTf salts (6a–d), while reactions with N,N′-dimesityl-1,4-diaza-1,3-butadiene give, except in the case of 1c, which is too bulky to react, the aza analogues, 1,4-dimesityl-6,9-diaryl-1,4,6,9-tetraaza-5-phosphoniaspiro[4.4]non-2-ene (7a, 7b and 7d). The sterically congested 7d is in thermal equilibrium with 1d and free diazadiene, and undergoes a substitution reaction with 2,3-dimethyl-1,3-butadiene to give 6d.
报道了一系列氟甲基磺酸盐(OTf)盐,含有苯基(1a)、对甲氧基苯基(1b)、2,6-二异丙基苯基(1c)和美克西尔(1d)取代基的N-杂环磷铵(NHP)。化合物1b–d的合成是对文献程序的改进,分别提高了1c和1d的总体产率15%和23%。在1d的合成中,有两个不希望的副产物被表征:二铵盐[(2,6-iPr-C6H3)N(H)2CH2CH2N(H)2(2,6-iPr-C6H3)]Cl2(4)和双磷(2,6-iPr-C6H3)N(PCl2)CH2CH2N(PCl2)(2,6-iPr-C6H3)(5),以及中间体环状氯磷化物C1PN(4-OMe-C6H4)CH2CH2N(4-OMe-C6H4)(3b)。苯基取代的NHP 1a首次被全面表征,包括X射线晶体学,该化合物含有一个短的P–O接触2.1850(14) Å。1a–d与2,3-二甲基-1,3-丁二烯的环加成反应给出预期的螺环磷铵,即7,8-二甲基-1,4-二芳基-1,4-二氮-5-磷酸螺[4.4]壬-7-烯,以其OTf盐(6a–d)形式存在,而与N,N′-双美克西尔-1,4-二氮-1,3-丁二烯的反应除1c因体积过大而无法反应外,得到了氮相似物1,4-双美克西尔-6,9-二芳基-1,4,6,9-四氮-5-磷酸螺[4.4]壬-2-烯(7a、7b和7d)。立体拥挤的7d与1d及自由二氮烯处于热平衡,并与2,3-二甲基-1,3-丁二烯发生取代反应生成6d。