非呐酮的烯醇三甲基硅醚在紫外光照下的氟烷基化反应

本文报导了卤代氟烷与酮的烯醇硅醚的反应. 用3,3-二甲基-2-丁酮的烯醇三甲硅醚与等摩尔的1,1,1-三氟-2,2,2-三溴乙烷及催化量的过氧化月桂酰进行紫外光照, 得到二个馏份化合物: 第一馏份为Me3SiBr, 第二馏份含三个化合物, 分别是2,2-二甲基-5,5-二溴6,6,6-三氟-3-己酮, 1,1,1-三氟-2-溴-5,5-二甲基-2-烯-4-己酮和3,3-二甲基-2-丁酮. 上述化合物与NaHCO3或NaOH水溶液反应生成α,β-烯酮(Cl(CF2)n-1CF=CHCOCMe3), 得率好.     

全氟和多氟烷基磺酸的研究XVIII.全氟烷磺酸二氟甲酯及其反应

和RFSO3CH2R(1)及RFSO3CF2RF'(2)不同,RFSO3CF2H(3)(RF=CF3,3a;ICF2CF2OCF2CF2,3b;Cl2CFCF2OCF2CF2,3c;ClCF2CF2OCF2CF2,3d)和亲核试剂的反应较为复杂。除X[-](X=F,Cl,I)及C2H5OH与3反应时只发生C-O键断裂外,其它试剂如RCO2[-],C6H5S[-]等既可进攻硫原子又可进攻碳原子,但以前者为主。碱性较强的试剂如RO[-]还可夺取二氟甲基的氢原子而产生二氟卡宾。在3中由于甲基碳上存在两个氟原子,确实有着一定的屏蔽作用,因此阻碍了某些试剂对它的亲核进攻,但由于这个碳上还连有一个氢原子,所以这种屏蔽作用并不完全。     

1,3-二碘六氟丙烷的电子转移反应

在四醋酸铅的催化下,二氟二碘甲烷(CF2I2,1)与四氟乙烯加成生成1,3-二碘六氟丙烷(ICF2CF2CF2I,3).3与烯烃、炔烃和丙二酸二乙酯阴离子发生电子转移反应。     

氟烷磺酰氟和全乙酰基保护的吡喃型半缩醛单糖的氟代反应

考察了5-氢-3-氧杂-1,1,2,2,4,4,5,5-八氟戊烷磺酰氟(HCF2CF2OCF2CF2SO2F)和全乙酰基保护的吡喃型半缩醛单糖在有机碱存在下的氟代反应.实验结果表明,氟烷基磺酰氟试剂HCF2CF2OCF2CF2SO2F能够诱导全乙酰基保护的吡喃型半缩醛单糖发生氟代反应而生成相应的氟代糖苷,得率44%～94%.该方法具有反应条件温和和后处理简便等优点,可作为一种有效的方法用于氟代糖苷的制备中.     

高对映选择性的有机催化的二氟烯醇硅醚与β,γ-不饱和-α-酮酸酯的不对称Mukaiyama-aldol反应

首次研究了二氟烯醇硅醚1与β,γ-不饱和酮酸酯2的反应.发现不论使用叔胺或叔胺-氢键给体双功能催化剂,均专一地发生Mukaiyama-aldol反应生成相应的叔醇3.利用手性氢化奎宁衍生的双功能脲催化剂11高对映选择性地实现了这一反应,为合成α-二氟烷基取代的手性叔醇提供了一种新方法.不同芳基取代的二氟烯醇硅醚以及γ位不同芳基取代的酮酸酯化合物均反应良好.在所考察的15个例子中,反应产率中等到良好(44%～81%),对映选择性中等到优秀(72%～96%).反应产物可方便转化为二氟烷基取代的手性二醇或三醇化合物.     

NaBH_4还原二氟乙酸乙酯合成二氟乙醇的研究

采用硼氢化钠(NaBH4)还原二氟乙酸乙酯(CF2HCOOCH2CH3)合成二氟乙醇(HCF2CH2OH)。探讨NaBH4用量、溶剂、反应温度和反应时间等因素对反应的影响。实验结果表明:在投料比n(NaBH4)/n(CF2HCOOCH2CH3)=0.6,乙醇为溶剂,温度0℃反应条件下,二氟乙醇的收率可以达到98.1%。在极性溶剂中,随着反应温度的升高(5℃及以上),NaBH4的分解加剧,低温对反应有利。     

(3＇→5＇)亚甲基缩醛连接的二聚和三聚体脱氧核苷的另法合成

3'-O-(甲硫甲基)缩醛的脱氧核苷(1)与N-碘代丁二酰亚胺(MS)和二苯基次膦酸反应得到相应的3＇-O-(二苯膦酰氧)甲基缩醛(2).在三甲基硅三氟甲磺酸酯(TMSOTf)的条件下,后者与3＇-位保护的脱氧核苷(5)缩合,得到(3＇→5＇)甲缩醛连接的二聚体d[(B1-m-B2)](m=次甲基)(6).同样的,2(B=T或B=C)与3＇-位保护的二聚体9(T-M-T或C-m-T)缩合,可得到相应的三聚体10(T-m-T-m-T,C-m-T-T和Y-m-C-m-T).     

片呐酮的烯醇三甲基硅醚在紫外光照下的氟烷基化反应

酮的烯醇硅醚的富电子碳碳双键易被亲电子基团进攻,生成取代酮类化合物。例如,在TiCl_4等Lewis酸的存在下,卤代烷与酮的烯醇三甲硅醚反应生成2-烷基取代酮。迄今为止,还没有卤代氟烷与酮的烯醇非醚反应研究的报道。我们将3,3-二甲基-2-丁酮的烯醇三甲硅醚与等摩尔的1,1,1-三氟-2,2,2-三溴乙烷及催化量的过氧化月桂酰进行光照3h后,б_F-10 ppm处出现一新峰,与CF_3CBr_3(2)的δ_F0 ppm处峰的面积比为2:3。继续光照,δ_F-     

Br?nsted酸性离子液体催化缩醛化反应合成聚甲氧基二烷基醚

聚甲氧基二烷基醚(RO(CH2O)nR)具有高的十六烷值(CN)和含氧量,能显著改善柴油的燃烧特性,有效提高热效率,大幅减少碳烟和NOx排放,被认为是一种优良的环保型燃油组分.随着–R基碳链的增长,CN值、热值和闪点逐渐增大,密度和冷凝点逐渐降低.同时,该类化合物具有优异的溶解及渗透性能,能与许多有机溶剂互溶,低毒,可以用作溶剂或颜料分散剂.近年来,聚甲氧基二甲基醚(CH3O(CH2O)nCH3,PODEn,DMMn)的制备及应用研究受到广泛关注,而对封端基团(–R)碳数大于1的多醚类化合物的研究鲜有文献报道.本文以Br?nsted酸性离子液体为催化剂,对甲醛和二乙氧基甲烷或脂肪醇(碳数 ≥2)缩醛化反应制备聚甲氧基二烷基醚的反应性能进行了研究,考察了离子液体结构和酸性对其催化性能的影响.结果表明,–SO3H功能化的离子液体[MIMBs]HSO4在催化三聚甲醛与二乙氧基甲烷的缩醛化反应中表现出最好的催化活性.考察了催化剂用量、原料配比、反应温度、反应压力和反应时间等因素对反应性能的影响,并得到了最佳反应条件,在n([MIMBs]HSO4):n(DEM1):n(HCHO)=1:80:80,140°C下反应4 h,甲醛转化率达到了92.6%,DEM2–8选择性为95.1%.考察了不同甲醛源(三聚甲醛和多聚甲醛)与提供封端基团化合物(二乙氧基甲烷、乙醇、丙醇和丁醇)的缩醛化反应.结果发现,在反应过程中不生成水或不引入水的条件下,具有更高的反应转化率和产物选择性.分别采用静置分层和萃取实现了催化剂的分离与重复使用.推测反应机理认为,三聚甲醛首先在氢键作用下分解生成甲醛单体,甲醛和二乙氧基甲烷通过碳正离子反应机理实现了DEMn的链增长.     

（3′→5′）亚甲基缩醛连接的二聚和三聚体脱氧核苷的另法合成

3′-O－（甲硫甲基）缩醛的脱氧核苷（1）与N－碘代丁二酰亚胺（NIS）和二苯基次膦酸反应得到相应的3′-O－（二苯膦酰氧）甲基缩醛（2）。在三甲基硅三氟甲磺酸酯(TMSOTf)的条件下,后与3′-位保护的脱氧核苷（5）缩合,得到（3′→5′)亚甲基缩醛连接的二聚体d[(B1-m-B2)](m=次甲基）（6）。同样的,2（B＝T或B＝C）与3′-位保护的二聚体9（T-m-T或C-m-T）缩合,可得到相应的三聚体10(T-m-T-m-T,C-m-T-m-T和T-m-C-m-T）。     

The Synthesis of Phosphonate Ester Containing Fluorinated Vinyl Ethers

Three novel perfluorovinyl ethers containing phosphonate ester groups, diethyl 1,1,2,2,3,3,5,6,6-nonafluoro-4-oxa-5-hexenylphosphonate, (EtO)(2)P(O)(CF(2))(3)OCF=CF(2) (1), diethyl 1,1,2,2,4,5,5-heptafluoro-3-oxa-4-pentenylphosphonate, (EtO)(2)P(O)(CF(2))(2)OCF=CF(2) (2), and diethyl 1,1,2,2,4,5,5,7,8,8-decafluoro-4-trifluoromethyl-3,6-dioxa-7-octenylphosphonate, CF(2)=CFOCF(2)CF(CF(3))O(CF(2))(2)P(O)(OEt)(2) (3), have been synthesized. Perfluorovinyl ethers 1 and 2 were synthesized from methyl 4-trifluoroethenoxy-2,2,3,3,4,4-hexafluorobutanoate and methyl 3-trifluoroethenoxy-2,2,3,3-tetrafluoropropanoate, respectively, while perfluorovinyl ether 3 was synthesized either from 5-trifluoroethenoxy-4-trifluoromethyl-3-oxa-1,1,2,2,4,5,5-heptafluoropentylsulfonyl fluoride or methyl 6-trifluoroethenoxy-5-trifluoromethyl-4-oxa-2,2,3,3,5,6,6-heptafluorohexanoate. The carboxylate esters were converted to the corresponding fluoroalkyl iodides via a free-radical iododecarboxylation. The sulfonyl fluoride was converted to its corresponding fluoroalkyl iodide via iododesulfination. The intermediate iodides were found to be useful precursors for the incorporation of the phosphonic ester groups via a photoreaction with tetraethyl pyrophosphite to produce diethyl fluorophosphonites. The diethyl fluorophosphonites were oxidized to the desired phosphonates, 1, 2, and 3, utilizing hydrogen peroxide as the oxidant. Moderate to good overall yields of perfluorovinyl ethers 1-3 have been achieved.     

Highly reduced, polyoxo(alkoxo)vanadium(III/IV) clusters

A family of high nuclearity oxo(alkoxo)vanadium clusters in unprecedentedly low oxidation states is reported, synthesised from simple vanadium diketonate precursors in alcohols under solvothermal conditions. Crystal structures of [V18(O)12(OH)2(H2O)4(EtO)22(O2CPh)6(acac)2] (1), [V16Na2(O)18(EtO)16(EtOH)2(O2CPh)6(HO2CPh)2]infinity (2), [V13(O)13(EtO)15(EtOH)(RCO2)3] in which R=adamantyl (3) or Ph3C (4), and [V11(O)12(EtO)13(EtOH)(Ph3CCO2)2(MePO3)] (5) are reported, revealing these to be {VIII 16VIV 2} (1), {VIII 9VIV 3VV} (3 and 4) and {VIII 3VIV 8} (5) clusters, while 2 consists of isolated {VIII 8VIV 8} clusters bridged into polymeric chains by {Na2(OEt)2} fragments. Solvothermal conditions are essential to the formation of these species, and the level of oxidation of the isolated clusters is in part controlled by the crystallisation time, with the lowest mean-oxidation-state species being isolated by direct crystallisation on controlled cooling of the reaction solutions.     

Synthesis, structures and reactivity of ruthenium nitrosyl complexes containing Kläui's oxygen tripodal ligand

Ruthenium nitrosyl complexes containing the Kl?ui's oxgyen tripodal ligand L(OEt)(-) ([CpCo{P(O)(OEt)(2)}(3)](-) where Cp = η(5)-C(5)H(5)) were synthesized and their photolysis studied. The treatment of [Ru(N^N)(NO)Cl(3)] with [AgL(OEt)] and Ag(OTf) afforded [L(OEt)Ru(N^N)(NO)][OTf](2) where N^N = 4,4'-di-tert-butyl-2,2'-bipyridyl (dtbpy) (2·[OTf](2)), 2,2'-bipyridyl (bpy) (3·[OTf](2)), N,N,N'N'-tetramethylethylenediamine (4·[OTf](2)). Anion metathesis of 3·[OTf](2) with HPF(6) and HBF(4) gave 3·[PF(6)](2) and 3·[BF(4)](2), respectively. Similarly, the PF(6)(-) salt 4·[PF(6)](2) was prepared by the reaction of 4·[OTf](2) with HPF(6). The irradiation of [L(OEt)Ru(NO)Cl(2)] (1) with UV light in CH(2)Cl(2)-MeCN and tetrahydrofuran (thf)-H(2)O afforded [L(OEt)RuCl(2)(MeCN)] (5) and the chloro-bridged dimer [L(OEt)RuCl](2)(μ-Cl)(2) (6), respectively. The photolysis of complex [2][OTf](2) in MeCN gave [L(OEt)Ru(dtbpy)(MeCN)][OTf](2) (7). Refluxing complex 5 with RNH(2) in thf gave [L(OEt)RuCl(2)(NH(2)R)] (R = tBu (8), p-tol (9), Ph (10)). The oxidation of complex 6 with PhICl(2) gave [L(OEt)RuCl(3)] (11), whereas the reduction of complex 6 with Zn and NH(4)PF(6) in MeCN yielded [L(OEt)Ru(MeCN)(3)][PF(6)] (12). The reaction of 3·[BF(4)](2) with benzylamine afforded the μ-dinitrogen complex [{L(OEt)Ru(bpy)}(2)(μ-N(2))][BF(4)](2) (13) that was oxidized by [Cp(2)Fe]PF(6) to a mixed valence Ru(II,III) species. The formal potentials of the RuL(OEt) complexes have been determined by cyclic voltammetry. The structures of complexes 5,6,10,11 and 13 have been established by X-ray crystallography.     

Titanium(IV) and zirconium(IV) sulfato complexes containing the Kläui tripodal ligand: molecular models of sulfated metal oxide surfaces

Treatment of titanyl sulfate in about 60 mM sulfuric acid with NaL(OEt) (L(OEt) (-)=[(eta(5)-C(5)H(5))Co{P(O)(OEt)(2)}(3)](-)) afforded the mu-sulfato complex [(L(OEt)Ti)(2)(mu-O)(2)(mu-SO(4))] (2). In more concentrated sulfuric acid (>1 M), the same reaction yielded the di-mu-sulfato complex [(L(OEt)Ti)(2)(mu-O)(mu-SO(4))(2)] (3). Reaction of 2 with HOTf (OTf=triflate, CF(3)SO(3)) gave the tris(triflato) complex [L(OEt)Ti(OTf)(3)] (4), whereas treatment of 2 with Ag(OTf) in CH(2)Cl(2) afforded the sulfato-capped trinuclear complex [{(L(OEt))(3)Ti(3)(mu-O)(3)}(mu(3)-SO(4)){Ag(OTf)}][OTf] (5), in which the Ag(OTf) moiety binds to a mu-oxo group in the Ti(3)(mu-O)(3) core. Reaction of 2 in H(2)O with Ba(NO(3))(2) afforded the tetranuclear complex (L(OEt))(4)Ti(4)(mu-O)(6) (6). Treatment of 2 with [{Rh(cod)Cl}(2)] (cod=1,5-cyclooctadiene), [Re(CO)(5)Cl], and [Ru(tBu(2)bpy)(PPh(3))(2)Cl(2)] (tBu(2)bpy=4,4'-di-tert-butyl-2,2'-dipyridyl) in the presence of Ag(OTf) afforded the heterometallic complexes [(L(OEt))(2)Ti(2)(O)(2)(SO(4)){Rh(cod)}(2)][OTf](2) (7), [(L(OEt))(2)Ti(O)(2)(SO(4)){Re(CO)(3)}][OTf] (8), and [{(L(OEt))(2)Ti(2)(mu-O)}(mu(3)-SO(4))(mu-O)(2){Ru(PPh(3))(tBu(2)bpy)}][OTf](2) (9), respectively. Complex 9 is paramagnetic with a measured magnetic moment of about 2.4 mu(B). Treatment of zirconyl nitrate with NaL(OEt) in 3.5 M sulfuric acid afforded [(L(OEt))(2)Zr(NO(3))][L(OEt)Zr(SO(4))(NO(3))] (10). Reaction of ZrCl(4) in 1.8 M sulfuric acid with NaL(OEt) in the presence Na(2)SO(4) gave the mu-sulfato-bridged complex [L(OEt)Zr(SO(4))(H(2)O)](2)(mu-SO(4)) (11). Treatment of 11 with triflic acid afforded [(L(OEt))(2)Zr][OTf](2) (12), whereas reaction of 11 with Ag(OTf) afforded a mixture of 12 and trinuclear [{L(OEt)Zr(SO(4))(H(2)O)}(3)(mu(3)-SO(4))][OTf] (13). The Zr(IV) triflato complex [L(OEt)Zr(OTf)(3)] (14) was prepared by reaction of L(OEt)ZrF(3) with Me(3)SiOTf. Complexes 4 and 14 can catalyze the Diels-Alder reaction of 1,3-cyclohexadiene with acrolein in good selectivity. Complexes 2-5, 9-11, and 13 have been characterized by X-ray crystallography.     

Mechanism of palladium-catalyzed diene cyclization/hydrosilylation: direct observation of intramolecular carbometalation

The results of kinetic, deuterium-labeling, and low-temperature NMR studies have established a mechanism for the palladium-catalyzed cyclization/hydrosilylation of dimethyl diallylmalonate (1) with triethylsilane involving rapid, irreversible conversion of the palladium silyl complex [(phen)Pd(SiEt(3))(NCAr)](+) [BAr(4)](-) [Ar = 3,5-C(6)H(3)(CF(3))(2)] (4b) and 1 to the palladium 5-hexenyl chelate complex [(phen)Pd[eta(1),eta(2)-CH(CH(2)SiEt(3))CH(2)C(CO(2)Me)(2)CH(2)CH=CH(2)]](+) [BAr(4)](-) (5), followed by intramolecular carbometalation of 5 to form the palladium cyclopentylmethyl complex trans-[(phen)Pd[CH2CHCH2C(CO2Me)2CH2CHCH2SiEt3](NCAr)]+ [BAr4]- (6), and associative silylation of 6 to release 3 and regenerate 4b.     

1-[Hydroxy(sulfonyloxy)iodo]-1H,1H-perfluoroalkanes: Stable, Fluoroalkyl Analogs of Koser's Reagent

1-[Hydroxy(sulfonyloxy)iodo]-1H,1H-perfluoroalkanes 3 [R(f)CH(2)I(OH)OSO(2)R; R = CH(3), CF(3), p-CH(3)C(6)H(4), R(f) = CF(3), C(2)F(5)] can be prepared in two steps from the appropriate iodofluoroalkanes by oxidation with peroxytrifluoroacetic acid and subsequent reaction with TsOH, MsOH, or Me(3)SiOTf. The tosylate derivative 3a reacts with silyl enol ethers under mild conditions to give the respective alpha-(tosyloxy) ketones. A similar reaction of cyclohexene furnishes cis-1,2-bis(tosyloxy)cyclohexane as the major product. Triflates 3c,f react with (trimethylsilyl)arenes under mild conditions to afford the respective (fluoroalkyl) (aryl)iodonium triflates 7, while the analogous reaction with alkynyltrimethylsilanes leads to novel (fluoroalkyl)(alkynyl)iodonium salts 8.     

The influence of perfluorinated substituents on the nucleophilic reactivities of silyl enol ethers

The fluorinated trimethylsilyl enol ethers 3a-c were synthesized, and the kinetics of their reactions with the benzhydrylium ions 4 was studied by UV-vis spectroscopy in dichloromethane. Comparison with nonfluorinated analogues shows that replacement of CH(3) by CF(3) reduces the nucleophilic reactivity by 8 orders of magnitude, while the exchange of C(6)H(5) by C(6)F(5) retards the reactions by 4.5 orders of magnitude.     

Palladium complex catalyzed acylation of allylic esters with acylsilanes.

Acylation of allylic esters (2) with acylsilanes (1) in the presence of a catalytic amount (5 mol %) of a palladium complex is reported. The reaction proceeds selectively to afford beta,gamma-unsaturated ketones (3) in high yields. [Pd(eta3-C6H5CH=CHCH2)(CF3COO)]2 (4a) showed the best catalytic activity. After the reaction, formation of CF3COOSiMe3 (5a) was confirmed by 29Si NMR measurement of the resulting reaction mixture, indicating the trimethylsilyl moiety effectively traps the CF3COO leaving group from 2. The leaving group of the allylic esters affects the reaction considerably: allylic trifluoroacetate gave the best result, while the corresponding acetates and trichloroacetates did not afford any acylation products at all. Stoichiometric reaction of 4a with 1 gave acylation product 3 with a formation of 5a and Pd(0), whereas no acylation reaction took place with the corresponding acetate complex [Pd(eta3-C6H5CH=CHCH2)(CH3COO)]2 (4b). A DFT calculation suggests that interaction of high-lying HOMO of 1 and low-lying LUMO of eta3-allylpalladium trifluoroacetate intermediate 4 would be indispensable in the catalytic cycle.     

Syntheses and experimental studies on the relative stabilities of spiro, ansa, and bridged derivatives of cyclic tetrameric fluorophosphazene

Reactions of (CF2CH2OSiMe3)2 and CF2(CF2CH2OSiMe3)2 with N4P4F8 (1) in a 1:2.5 molar ratio resulted in the formation of monospiro compounds [(CF2CH2O)2PN](F2PN)3 (2) and [CF2(CF2)CH2O)2PN](F2PN)3 (4) as well as the intermolecular bridged compounds F7N4P4OCH2CF2CF2CH2OP4N4)F7 (3) and F7N4P4OCH2CF2CF2CF2CH2OP4N4F7 (5). An equimolar reaction of dilithiated 1,3-propanediol with 1 resulted in the 1,3-ansa-substituted compound CH2(CH2O)2[P(F)N]2(F2PN)2 (6) as the major product in good yield. However, an analogous reaction of the dilithiated 1,3-propanedithiol with 1 gave only the spirocyclic compound CH2(CH2S)2(PN)(F2PN)3 (8). The molecular structures of 2 and 6 were determined by single-crystal X-ray diffraction. In the presence of catalytic amounts of CsF in THF, the bridged compound 3 was converted to the spirocyclic compound 2 while the 1,3-ansa compound 6 under similar conditions transformed into the monospiro-substituted compound CH2(CH2O)2 (PN)(F2PN)3 (7). These transformations were monitored by time-dependent 19F and 31P NMR studies.