ライフサイエンスコーパス: HMPA

1 HMPA greatly decelerated the reaction of 1S (<10 -10), p

2 HMPA in large amounts promotes dissociation to monomer w

3 HMPA is known to increase the reduction potential of SmI

4 I(Me))(THF) (1), Cp*U((Mes)PDI(Me))(HMPA) (1-HMPA), and Cp*U((t)Bu-(Mes)PDI(Me))(THF) (1-(t)Bu).

5 A solution of 1-Li in THF containing 10% HMPA is much more reactive in alkylation than 1-Li alone

6 of alpha-methylalkenes with V(2)O(3)Dipic(2)(HMPA)(2) and chloramine T as the quantitative source of

7 sm of [Sm[N(SiMe(3))(2)](2)]-HMPA and SmI(2)-HMPA reductions are presented.

8 success of this cyclization; and (d) SmI(2)-HMPA-mediated regio- and stereoselective reduction of th

9 those that classic reductants (e.g., SmI(2)/HMPA) have failed to promote.

10 into the mechanism of [Sm[N(SiMe(3))(2)](2)]-HMPA and SmI(2)-HMPA reductions are presented.

11 While the [Sm[N(SiMe(3))(2)](2)]-HMPA combination results in a more powerful reductant ba

12 bly deaggregated by TMEDA or PMDTA, although HMPA causes partial deaggregation.

13 for reaction with allyl bromide implicate an HMPA-solvated ion pair with a (+)Li(HMPA)(4) counterion.

14 d by the nonlabile ligand -N(SiMe(3))(2) and HMPA around the Sm metal.

15 reactions of BnO(*) with DMSO/DMSO-d(6) and HMPA/HMPA-d(18), together with the k(H)(BnO(*))/k(H)(Cum

16 tion of this radical with DMSO/DMSO-d(6) and HMPA/HMPA-d(18).

17 rt Z-5F-Li to a monomeric amine complex, and HMPA converts it partially to monomers, and partially to

18 e containing enolate, lithium hydroxide, and HMPA in a 4:2:4 ratio, [(LiOPin)4.(LiOH)2.HMPA4], that w

19 The combination of visible light and HMPA was found in some cases to be synergistic, in other

20 ithium diisopropyl amide, lithium oxide, and HMPA in the ratio 5:1:1:2 is also described.

21 fect of cosolvents such as TMEDA, PMDTA, and HMPA has also been determined.

22 External additives such as HMPA, tributylphosphine, or dialkylzinc are not necessar

23 uction of ketones by SmI(2) (and SmI(2)[bond]HMPA complexes) and an outer-sphere-type ET for the redu

24 on of alkyl iodides by SmI(2) or SmI(2)[bond]HMPA complexes.

25 e highly reactive separated ion pair t-Bu(-)/HMPA(4)Li(+).

26 nclude the triple ion pair (t-Bu-Li-t-Bu)(-)/HMPA(4)Li(+) which serves as a reservoir for the highly

27 alkyl halides is generally C-alkylation but HMPA promotes increasing amounts of O-alkylation.

28 tion of 2-(phenylsulfonyl)indane followed by HMPA-assisted E1cB-elimination of phenylsulfinate.

29 erature activation of the silicon reagent by HMPA to generate difluorocarbene, which upon interacting

30 The cosolvent HMPA formed monomers along with minor amounts of lithiat

31 diethyl ether; dipolar ligands such as DMF, HMPA, DMSO, and DMPU; a bifunctional dipolar ligand nona

32 strong hydrogen bond acceptors such as DMSO, HMPA, and tributylphosphine oxide (TBPO) by the cumyloxy

33 or the aryl-substituted enolates at elevated HMPA concentrations.

34 anistic approach enabled catalysis employing HMPA as a ligand, facilitating the development of cataly

35 Excess HMPA leads to the formation of ca. 15% of a triple ion (

36 diethyl ether even in the presence of excess HMPA.

37 Due to a small amount of moisture from HMPA or air leaking into the solution, a minor complex w

38 one reduction by Sm is unaffected by further HMPA addition while a linear dependence of ET rate on th

39 de (LDA) with added hexamethylphosphoramide (HMPA) are described.

40 olutions with added hexamethylphosphoramide (HMPA).

41 iamine (TMCDA), and hexamethylphosphoramide (HMPA).

42 quid ammonia and in hexamethylphosphoramide (HMPA) to form indantrione, which has a sufficiently larg

43 raeneoxypropane, in hexamethylphosphoramide (HMPA), yields an anion radical, which disproportionates

44 was determined that hexamethylphosphoramide (HMPA) can shift the equilibrium of t-BuLi to include the

45 of ligand displacement (exchange) in Sm(II)-HMPA-based reactions and insight into the mechanism of [

46 ate ketyl to the sterically congested Sm(III)HMPA both stabilizes the intermediate and inhibits cycli

47 In HMPA, cyclopentene oxide undergoes beta-elimination.

48 In HMPA, the indantrione anion radical spontaneously forms

49 rine with lithium fluoride and 15-crown-5 in HMPA.

50 e trianion radical of C60 reacts with COT in HMPA to yield a [2 + 2] cycloaddition product, and subse

51 omanes by thermal 6pai-electrocyclization in HMPA followed by in situ aromatization.

52 = phenyl, beta-naphthyl, alpha-naphthyl), in HMPA, results in anion radicals that undergo novel intra

53 and 1-naphthyl) in THF with 18-crown-6 or in HMPA results in the formation of the corresponding triar

54 Conversely, reactions were first-order in HMPA, and the additive displayed saturation kinetics at

55 ert-butylcyclohexene oxide was rearranged in HMPA and was found to react via anti beta-elimination, a

56 A variety of NMR experiments, including HMPA titration, diffusion coefficient-formula weight (D-

57 Deprotonation of norbornene epoxide by LDA/HMPA proceeds via an intermediate metalated epoxide as a

58 Conjugate addition of LDA/HMPA to an unsaturated ester proceeds via di- and tetra-

59 icate an HMPA-solvated ion pair with a (+)Li(HMPA)(4) counterion.

60 m acetylide ethylenediamine complex (LiAEDA, HMPA, -5 degrees C), and benzyl group cleavage (Ac2O, Py

61 presence of the sterically demanding ligand HMPA.

62 ures, HMPA-bridged trisolvated dimers at low HMPA concentrations, and disolvated monomers for the ary

63 U((Mes)PDI(Me))(THF) (1), Cp*U((Mes)PDI(Me))(HMPA) (1-HMPA), and Cp*U((t)Bu-(Mes)PDI(Me))(THF) (1-(t)

64 tric dimers in THF and THF/toluene mixtures, HMPA-bridged trisolvated dimers at low HMPA concentratio

65 ion of an aryl carbamate proceeds via a mono-HMPA-solvated monomer-based pathway.

66 eric structures in THF/Et(2)O and THF/Et(2)O-HMPA by study of the effects of the addition of HMPA.

67 logous eliminations in THF in the absence of HMPA.

68 red to understand the mechanism of action of HMPA on various substrates.

69 The addition of HMPA had no effect on the rate of reaction of the triple

70 astereomeric product ratios upon addition of HMPA suggest that complexation of HMPA to lithium has tw

71 Addition of HMPA to [Sm[N(SiMe(3))(2)](2)] produces a less reactive

72 eactive reductant in contrast to addition of HMPA to SmI(2).

73 n triol exclusively (by 1H NMR); addition of HMPA to the reaction or replacement of the substrate's m

74 solvation (generally through the addition of HMPA).

75 A by study of the effects of the addition of HMPA.

76 yclization is driven by the high affinity of HMPA for Sm(III), and these results suggest that simple

77 F solution, but addition of small amounts of HMPA causes a bathochromic shift in the spectrum of 1-Li

78 ddition of HMPA suggest that complexation of HMPA to lithium has two effects.

79 A derivative of HMPA in which one of the methyl groups was substituted b

80 The effect of HMPA on the electron transfer (ET) rate of samarium diio

81 ocarbon solution when more than 0.6 equiv of HMPA is present.

82 lfur-stabilized lithium reagents, 2 equiv of HMPA suffice to achieve >95% 1,4 addition, whereas 4 equ

83 After the addition of 4 equiv of HMPA the ET rate and activation parameters for ketone re

84 compound is fully deaggregated by 1 equiv of HMPA.

85 air through displacement by an equivalent of HMPA provides a solvent-separated ion pair releasing the

86 dependence of ET rate on the equivalents of HMPA was found in the SmI(2)/alkyl iodide system.

87 in the presence of different equivalents of HMPA were compared to understand the mechanism of action

88 The mechanistic importance of HMPA and proton donors (methanol, 2-methyl-2-propanol, a

89 e quantitative effect of small increments of HMPA indicates that 1-Li is a dimer.

90 oted by samarium diiodide in the presence of HMPA and acetone allow access to the fully functionalize

91 f HMPA, and (c) reactions in the presence of HMPA in the dark.

92 adiation, (b) irradiation in the presence of HMPA, and (c) reactions in the presence of HMPA in the d

93 enzotriazole (5) and LDA, in the presence of HMPA, reacts with enolizable and nonenolizable carbonyls

94 In the presence of HMPA, the rate order of proton donors was zero and produ

95 mple empirical models describing the role of HMPA in more complex systems are likely to be fraught wi

96 rily to the allenyl product while the use of HMPA as a cosolvent gives the beta,gamma-alkynyl deconju

97 In this tetramer one HMPA binds to lithium more strongly than the other two c

98 ably converted to monomer either by PMDTA or HMPA.

99 The role of polar solvents (particularly HMPA) in controlling the ratio of 1,2 to 1,4 addition of

100 ammetry studies have shown that it resembles HMPA in its ability to enhance the reduction potential o

101 The mechanistic complexity of the SmI2-HMPA-initiated ketyl-olefin cyclization is driven by the

102 ity to extract an electron from the solvent (HMPA) to produce the indantrione anion radical.

103 he crystal structure of a substoichiometric, HMPA-trisolvated lithium pinacolone enolate tetramer (Li

104 A tetra-HMPA-solvated lithium cyclopentanone enolate tetramer wa

105 unsaturated ester proceeds via di- and tetra-HMPA-solvated dimers.

106 ate that these salts are aggregated and that HMPA breaks up the aggregates of 1-Li.

107 chanism derived from rate studies shows that HMPA is important not only in increasing the reduction p

108 comes directly attached to a nitrogen of the HMPA.

109 he immediate product of the reaction was the HMPA-solvated separated ion 1S, with the Peterson produc

110 neously forms condensation products with the HMPA to produce a variety of zwitterionic radicals, wher

111 aromatic radical anions in the solvents THF, HMPA, and DMPU (dimethylpropyleneurea).

112 lithiums and phenylthiobenzyllithiums in THF-HMPA solutions.

113 ions are carried out at -78 degrees C in THF-HMPA, they proceed in 65-81% yields, with both regiocont

114 resence of cosolvent additives PMDTA, TMTAN, HMPA, and cryptand [2.1.1].

115 cm-1 in DMF and 400 cm-1 in MeCN compared to HMPA.

116 Once coordinated to HMPA, Sm(3+) is less capable of assisting in the protona

117 s can be achieved with acrylate esters using HMPA/TMSCl activation.

118 r arylation of a secondary sulfonamide using HMPA as solvent, multiple functional group interconversi

119 These results were consistent with HMPA being involved in a rate-limiting step before cycli

120 0(3), and 1.6 x 10(4) for the reactions with HMPA, TBPO, and DMSO, respectively.

121 quiv of lithium diisopropylamide in THF with HMPA as the cosolvent followed by trapping with a variet