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SCIENCE CHINA Chemistry, Volume 62, Issue 5: 571-582(2019) https://doi.org/10.1007/s11426-018-9403-7

Rare-earth metal catalysts for alkene hydrosilylation

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  • ReceivedOct 31, 2018
  • AcceptedDec 11, 2018
  • PublishedFeb 22, 2019

Abstract

Rare-earth metal catalyzed hydrosilylation of alkenes has emerged as a powerful and selective strategy for the synthesis of organosilanes. This transformation can offer distinctive catalytic sequences and reaction patterns from other catalysts because of the high electropositivity and lack of oxidative-addition process of rare-earth metal. This review summarizes the rare-earth metal catalysts for hydrosilylation of alkene according to the type of ligands. The synthesis and structure of rare-earth metal catalysts, the substrate scope as well as some preliminary structure-activity relationship and mechanism are discussed.


Funded by

the National Natural Science Foundation of China and Natural Science Foundation of Tianjin(21632006,21472098,16JCQNJC05800)


Acknowledgment

This work was supported by the National Natural Science Foundation of China (21632006, 21472098) and Natural Science Foundation of Tianjin (16JCQNJC05800).


Interest statement

The authors declare that they have no conflict of interest.


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  • Figure 1

    Structure of chiral half-sandwich scandium catalyst 3.

  • Scheme 1

    Metal-catalyzed hydrosilylation of alkene.

  • Figure 2

    Structures of alkyl and hydride yttrium complexes 28 and 29.

  • Scheme 2

    Generally proposed catalytic mechanism of alkene hydrosilylation by rare-earth metal catalysts.

  • Scheme 3

    The synthesis of catalyst 1.

  • Scheme 4

    The possible reaction pathways of 1,5-hexadiene hydrosilylation.

  • Scheme 5

    The synthesis of catalysts 58.

  • Scheme 6

    The reactions of 10 and 11 with PhSiH3.

  • Scheme 7

    The synthesis of catalysts 14 and 15.

  • Scheme 8

    The synthesis and catalytic activity of trimeric yttrium hydride 19.

  • Scheme 9

    The synthesis of catalyst 20.

  • Scheme 10

    The synthesis of catalysts 22 and 23.

  • Scheme 11

    The synthesis of catalyst 26.

  • Scheme 12

    Reaction of complex 26 with phenylsilane.

  • Scheme 13

    The synthesis of catalyst 30.

  • Scheme 14

    The synthesis of alkyl and hydride samarium complexes 31 and 32.

  • Scheme 15

    The synthesis of catalyst 33.

  • Scheme 16

    The synthesis and reactivity of complex 34.

  • Table 1   Catalytic hydrosilylation of alkenes with PhSiH by

    Entry

    Alkene

    Time

    Yield (%)

    Product

    ratio b)

    1

    3 d

    95

    95:5

    2 c)

    5 h

    >99

    85:15 d)

    3

    17 h

    97

    >99:1

    4

    10 h

    >99

    7:93

    Reaction conditions: alkene (1.0 mmol), PhSiH3 (1.1 mmol), 1 (0.02 mmol), in toluene, at room temperature; b) ratio of anti-Markovnikov product to Markovnikov product; c) Ph2SiH2 (1.1 mmol) was used instead of PhSiH3; d) ratio of PhSiHCH2(CMe=CH)Me to PhSiHCH2(CH=C)Me2.

  • Table 2   Hydrosilylation of various alkenes with 2,3-dihydro-1-benzo[]silole by

    R1=C5H11

    R1=iPr

    R1=tBu

    R1=Ph

    R1=4-BrC6H4

    R1=2,6-Cl2C6H3CH2

    97%, e.r.=97:3

    95%, e.r.=97:3

    95%, e.r.=97:3

    94%, e.r.=96:4

    92%, e.r.=96:4

    96%, e.r.=94:6

    R2=H

    R2=4-Me

    R2=4-MeO

    R2=4-PPh2

    R2=4-(1-piperidinyl)

    93%, e.r.>99:1 b)

    92%, e.r.=96:4 b)

    90%, e.r.=95:5 b)

    88%, e.r.=97:3 b)

    90%, e.r.=98:2 c)

    Reaction conditions: silane (0.10 mmol), alkene (0.11 mmol), 3(2.5 mol%), C6D6(0.8 mL) in a Schlenk NMR tube. Yield of isolated product. Exclusive linear selectivity was observed in all reactions. The e.r. values were determined by HPLC analysis on a chiral stationary phase. b) 85 °C, 36 h. c) 85 °C, 24 h. d) Silane (0.21 mmol) and alkene (0.10 mmol).

  • Table 3   Alkene hydrosilylation with various secondary silanes by

    Reaction conditions: R1SiH2Me (0.30 mmol), alkene (0.10 mmol), 3 (2.5 mol%), C6D6 (0.8 mL) in a Schlenk NMR tube. Yields of isolated product. Exclusive linear selectivity was observed in all reactions. The e.r. values were determined by HPLC analysis on a chiral stationary phase. b) 85 °C, 72 h. c) 65 °C,12 h.

  • Table 4   Catalytic hydrosilylation of alkenes with PhSiH by

    Entry

    Alkene

    T (°C)

    Time (h)

    Yield (%)

    M:aM b)

    1

    25

    40

    98

    4:96

    2

    25

    5

    99

    >99:1

    3

    25

    12

    99

    >99:1

    4

    60

    11

    99

    >99:1

    5

    25

    24

    <5

    Reaction conditions: 3 mol% of catalyst 4 in 1 mL C6D6; b) ratio of Markovnikov product to anti-Markovnikov product.

  • Table 5   Catalytic hydrosilylation of dienes with PhSiH by

    Entry

    Diene

    T (°C)

    Time

    (h)

    Product

    Yield

    (%)

    1

    25

    24

    99

    2

    60

    9

    95

    3

    60

    24

    95

    4 b)

    25

    48

    95

    Reaction conditions: 3 mol% of catalyst 4 in 1 mL C6D6; b) isomeric ratio is 4:2.

  • Table 6   Catalytic hydrosilylation of alkenes with PhSiH by

    Entry

    Alkene

    Time (h)

    Product

    Yield b)(%)

    aM:M c)

    1

    16

    99

    99:1

    2

    24

    99

    99:1

    3

    22

    99

    99:1

    4

    30

    99

    35:65

    5

    36

    99

    Reaction conditions: 1.5 mol% of catalyst 5 in 0.7 mL C6D6 at room temperature; b) calculated by 1H NMR; c) ratio of anti-Markovnikov product to Markovnikov product.

  • Table 7   Catalytic hydrosilylation of 1-hexene with PhSiH by –

    Entry

    Cat.

    Cat. loading (mol%)

    T (°C)

    Time (h)

    Yield b)(%)

    aM:M c)

    1

    6

    1.5

    100

    26

    99

    99:1

    2

    5

    1.5

    r.t.

    16

    99

    99:1

    3

    7

    1.5

    100

    6

    99

    99:1

    4

    8

    1.5

    100

    32

    99

    99:1

    5

    9

    3

    r.t.

    20

    99

    99:1

    6

    4

    3

    r.t.

    40

    98

    96:4

    Catalyst 9 is La[N(SiHMe2)2]3(THF)2; b) calculated by 1H NMR; c) ratio of anti-Markovnikov product to Markovnikov product.

  • Table 8   Product distribution in the catalytic hydrosilylation of 1,1-diphenylethylene with PhSiH by and

    Entry

    Cat.

    Solvent

    Time (h)

    M (%)

    aM (%)

    Ph2CHMe (%)

    1

    10

    4

    99

    0

    1

    2

    10

    THF

    4

    95

    0

    5

    3

    11

    5

    79

    2

    19

    4

    11

    THF

    4

    53

    5

    42

    Reaction conditions: 5 mol% of catalyst 10 and 11 at 50 °C.

  • Table 9   Catalytic hydrosilylation of alkenes with PhSiH by and

    Entry

    Alkene

    Cat.

    Time (min)

    Conv. b) (%)

    aM:M c)

    1

    2021

    <5

    <5

    100

    100

    >99:1

    >99:1

    2

    2021

    <5

    <5

    100

    100

    >99:1

    >99:1

    3

    2021

    <5

    <5

    100

    100

    >99:1

    >99:1

    4

    2021

    <5

    <5

    100

    100

    >99:1

    >99:1

    5

    2021

    300

    60

    98

    100

    >99:1

    >99:1

    6

    2021

    <5

    90

    100

    100

    >99:1

    >99:1

    7

    2021

    240

    720

    98

    98

    96:4

    96:4

    8

    2021

    25

    90

    100

    100

    26:74

    7:93

    9 d)

    2021

    70

    190

    100

    100

    33:67

    23:77

    Reaction conditions: catalyst 20 or 21 (2 mol%, 10 µmol), alkene (0.5 mmol), PhSiH3 (0.52 mmol), 23 °C, solvent C6D6 (0.3 mL); b) determined by GC-MS and in situ 1H NMR spectroscopy; c) ratio of anti-Markovnikov product to Markovnikov product; d) 80 °C.

  • Table 10   Catalytic hydrosilylation of alkenes by and

    Entry

    Alkene

    Silane

    Cat.

    Time (h)

    Yield b) (%)

    1

    1-Hexene

    PhSiH3

    24

    2

    >98

    2 c)

    Cyclohexene

    PhSiH3

    24

    16

    59

    3 c)

    Cyclohexene

    PhSiH3

    24

    68

    74

    4 d)

    1-Hexene

    PhMeSiH2

    24

    130

    >98

    5 d)

    Cyclohexene

    PhMeSiH2

    24

    84

    0

    6 e)

    1-Hexene

    PhSiH3

    25

    5 min

    >98

    7

    Cyclohexene

    PhMeSiH2

    25

    16

    16

    8 f)

    1-Hexene

    PhMeSiH2

    25

    20

    68

    9 f)

    Cyclohexene

    PhMeSiH2

    25

    24

    0

    Reaction conditions: catalyst 24 or 25 (5 mol%, 10 µmol), 23 °C, solvent C6D6; b) determined by 1H NMR spectroscopy; c) 23 °C; d) 80 °C; e) 2 mol% of 25; f) 40 °C.

  • Table 11   Catalytic hydrosilylation of vinylarenes by

    Product

    R

    T (oC)

    Time (h)

    Yield b) (%)

    Regiosel. c)(%)

    Ph d)

    60

    4

    95

    99.9

    C6H13 d)

    60

    4

    97

    99.9

    Cy e)

    70

    5

    95

    99.9

    Ph d)

    60

    4

    95

    98

    C6H13 d)

    60

    4

    97

    98

    Cy e)

    70

    5

    95

    98

    Ph d)

    60

    6

    95

    99.9

    C6H13 d)

    60

    6

    95

    99

    Cy e)

    80

    6

    95

    99.5

    Ph e)

    70

    6

    92

    96

    C6H13 e)

    70

    6

    92

    98

    Cy e)

    90

    8

    90

    98

    Ph e)

    70

    8

    93

    99

    C6H13 e)

    70

    8

    93

    99

    Cy e)

    90

    8

    90

    99.8

    Ph d)

    70

    6

    90

    99

    C6H13 d)

    70

    8

    90

    99

    Cy e)

    90

    8

    90

    99

    Reaction conditions: alkene (1.0 mmol), silane (1.0 mmol), 0.2 mL toluene; b) the yield is isolated yield; c) the regioselectivity was determined by GC-MS analysis; d) 0.5 mol% of 26; e) 1 mol% of 26.

  • Table 12   Catalytic hydrosilylation of aliphatic alkenes by

    Product

    R

    T (oC)

    Time (h)

    Yield b)(%)

    Regiosel.c)(%)

    Ph d)

    70

    6

    90

    97

    C6H13 d)

    70

    8

    95

    97.5

    Cy

    90

    8

    90

    97

    Ph d)

    70

    6

    90

    99

    C6H13 d)

    70

    8

    95

    98

    Cy

    90

    8

    90

    97

    Ph

    70

    6

    70

    98

    C6H13

    70

    8

    92

    98

    Cy

    90

    8

    93

    99

    Ph

    70

    6

    90

    99

    C6H13

    70

    8

    95

    98

    Cy

    90

    8

    93

    99

    Ph

    70

    6

    75

    97

    C6H13

    70

    8

    95

    98.5

    Cy

    90

    8

    95

    98

    Ph

    70

    6

    80

    97

    C6H13

    70

    8

    95

    98

    Cy

    90

    8

    95

    98

    Ph

    70

    6

    70

    95

    C6H13

    70

    8

    80

    97

    Cy

    90

    8

    80

    95

    Reaction conditions: 1 mol% of 26, alkene (1.0 mmol), silane (1.0 mmol), 0.2 mL toluene; b) the yield is isolated yield; c) the regioselectivity was determined by GC-MS analysis; d) 0.5 mol% of 26; e) silane (2.0 mmol).

  • Table 13   Catalytic hydrosilylation of alkenes by

    Entry

    Alkene

    Silane

    Turnover rate b)

    (h−1)

    aM:M c)

    1

    PhSiH3

    PhMeSiH2

    ~100

    4.3

    92:8

    >99:1

    2

    PhSiH3

    PhMeSiH2

    0.66

    0.12

    24:76

    36:64

    3

    PhSiH3

    ~30

    (90% ee)

    Reaction conditions: 5 mol% of catalyst, in C6D6 at room temperature; b) calculated by 1H NMR; c) ratio of anti-Markovnikov product to Markovnikov product.

  • Table 14   Catalytic hydrosilylation of alkenes with PhSiH by

    1 h, 99% yield b)

    >99.9% regiosel. c)

    1.5 h, 96% yield

    >99.9% regiosel.

    3 h, 88% yield

    >99.9% regiosel.

    5 h, 95% yield

    >99.0% regiosel.

    5 h, 99% yield

    >99.0% regiosel.

    3 h, 92% yield

    >99.0% regiosel.

    3 h, 97% yield

    >99.1% regiosel.

    3 h, 93% yield

    >99.9% regiosel.

    5 h, 95% yield

    >99.0% regiosel.

    Reaction conditions: 2.5 mol% of catalyst, in 1 mL toluene at 60 °C; b) isolated yield; c) regioselectivity was analyzed by GC-MS of the crude reaction mixture.

  • Table 15   Catalytic hydrosilylation of internal alkenes with hexylsilane by

    Reaction conditions: 3 mol%–5 mol% of 31, 0.5 mmol of alkenes and 0.55 mmol of RSiH3 (R=nC6H13) in 0.1 mL of toluene. The yield referred to the isolated yield and the percent in parenthesis referred the regioselectivity determined by GC-MS measurement of the crude products.

  • Table 16   Catalytic hydrosilylation of alkenes with PhSiH by and

    Entry

    Alkene

    Cat.

    Time (h)

    Conv. b) (%)

    aM:M c)

    1

    34d)

    22

    79

    2

    34d)

    35

    22

    66.5

    87

    81

    97:3

    98:2

    3

    34

    35

    2

    6.7

    95

    82

    6:94

    5:95

    Reaction conditions: 2 mol% of catalyst, in C6D6 at 60 °C; b) calculated by 1H NMR; c) ratio of anti-Markovnikov product to Markovnikov product; d) 4 mol% of catalyst.

  • Table 17   Catalytic hydrosilylation of alkenes by –

    Entry

    Cat.

    RSiH3

    Alkene

    Time

    T (°C)

    aM:M b)

    1

    36

    Ph

    1-Hexene

    18 h

    25

    94:6

    2

    37

    Ph

    1-Hexene

    14 h

    50

    93:7

    3

    38

    Ph

    1-Hexene

    9 h

    50

    93:7

    4

    39

    Ph

    1-Hexene

    16 h

    50

    95:5

    5

    36

    Ph

    1,5-Hexadiene

    48 h

    25

    95:5

    6

    37

    Ph

    1,5-Hexadiene

    14 h

    50

    91:9

    7 c)

    37

    nBu

    1,5-Hexadiene

    20 h

    50

    38:62

    8

    38

    Ph

    1,5-Hexadiene

    10 h

    50

    93:7

    9 d)

    38

    nBu

    1,5-Hexadiene

    17 h

    50

    67:33

    10

    36

    Ph

    Styrene

    <30 min

    25

    3:97

    11

    37

    Ph

    Styrene

    <20 min

    25

    3:97

    12

    38

    Ph

    Styrene

    3 h

    25

    5:95

    13

    39

    Ph

    Styrene

    7 h

    50

    6:94

    14 e)

    37

    Ph

    trans-Stilbene

    14 h

    50

    Reaction conditions: 2.5 mol% of catalyst, a silane/alkene ratio of 1.03:1 in C6D6 with a drop of [D8]THF. Conversion is >99% and calculated by 1H NMR spectroscopy. b) Ratio of anti-Markovnikov product to Markovnikov product. c) Conversion is 90%. d) Conversion is 92%. e) Conversion is 51%.

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