ca01 only detailed ToC 1..24

More documents

Recommendations

Info

40 Science of Synthesis 1.1 Organometallic Complexes of Nickel then transferred by cannula onto the [Ni(cod) 2]. The resulting purple-red slurry was stirred for 10 min and then treated with TMSCl (462 ìL, 3.64 mmol, 2.00 equiv) to afford a deep red soln. After 45 min, the volatiles were removed at 0.1 Torr to obtain an orange-red powder. This was extracted with pentane (20 mL) through a filter paper tipped cannula. The clear red filtrate was concentrated under vacuum to ca. 5 mL and then cooled to –208C for 24 h to induce crystallization. The precipitate was isolated by removal of the supernatant through a filter paper tipped cannula while maintaining the mixture at –208C, and washed with pentane (2 ” 3 mL) to afford 25 as a burgundy-red crystalline solid; yield: 0.35 g (86%). [(1,2,3-ç)-1-(tert-Butyldimethylsiloxy)cyclopentenyl]chlorobis(pyridine)nickel(II) (27): [38] A 100-mL Schlenk tube equipped with a magnetic stirring bar and rubber septum was charged with [NiCl 2(py) 4](26; 10.0 g, 22.4 mmol, 1.00 equiv) and evacuated and refilled with N 2 twice to establish an inert atmosphere. THF (40 mL) was added, followed by cycloocta-1,5-diene (8.20 mL, 67.2 mmol, 3.00 equiv), and the resulting mixture was cooled to 0 8C. A second 100-mL Schlenk tube containing Na metal strips (1.03 g, 44.8mmol, 2.00 equiv; each ca. 2 cm ” 0.4 cm ” 0.1 cm) was connected to this flask with a flexible adapter (available from Aldrich) under a rapid flow of N 2 (an inert atmosphere having previously been established in the second Schlenk tube and adapter by capping the free end of the adapter and evacuating and refilling with N 2). The Na strips were then transferred to the stirred 0–5 8C mixture in four portions over 1.5 h to give, after an additional 40 min at 0–5 8C, a very dark brown (but not black) supernatant, a small amount of precipitated yellow [Ni(cod) 2], and no apparent blue [NiCl 2(py) 4]. This was treated with a soln of cyclopent-2enone (1.88mL, 22.4 mmol, 1.00 equiv) and TBDMSCl (3.38g, 22.4 mmol, 1.00 equiv) in THF (15 mL) and stirred at 258C for 30 min to afford an orange mixture. The soln of 27 thus obtained was directly used in coupling reactions; no purification or yield was reported. 1.1.2.4 Method 4: Oxidative Cyclization of Nickel(0) Complexes of Conjugated Dienes ð-Allyl complexes are comm<strong>only</strong> invoked as intermediates in the reactions of (ç 4 -diene)nickel complexes. If a nickel(0) complex possesses both a conjugated diene ligand and another ð-bound ligand, an oxidative cyclization may occur to form a ð-allyl ligand within a nickel(II) metallacycle. Much of the [4+4]- and [4 +2]-cycloaddition chemistry described for ç 4 -diene complexes probably involves the intermediacy of nickel metallacycles that possess a ç 3 -allyl ligand. Oxidative cyclizations of this type are also useful in the stoichiometric preparation of nickel–ð-allyl complexes. The spectator ligand properties play a significant role in determining the position of the equilibrium for oxidative cyclization–reductive cleavage processes (Scheme 15). [40] Scheme 15 Ligand Dependence in the Formation of ð-Allyl Complexes by Oxidative Cyclization [40] CO2Me + Ni(cod)2 + Ph3P MeO2C Ph3P Ni 2 MeO2C CO 2Me + Ni(cod) 2 + bipy 2 MeO2C MeO 2C Ni(bipy)
1.1.2 Nickel–Allyl Complexes 41 Applications of Product Subclass 2 in Organic Synthesis 1.1.2.5 Method 5: Coupling of Allyl Halide Derived Nickel–Allyl Complexes with Alkyl Halides and Other Electrophiles Dimeric chloro-bridged nickel–ð-allyl complexes (e.g, 28) undergo a facile coupling reaction with a variety of electrophiles. Highly polar solvents are required, and light is often used to initiate the process. Interestingly, sp 2 -hybridized halides are more reactive than sp 3 -hybridized halides. Coupling generally occurs at the less-substituted terminus of the ð-allyl complex. Whereas couplings with aryl, alkenyl, and alkyl halides are often quite efficient, leading to products such as 29 (Scheme 16), couplings between nickel–ð-allyl complexes and allylic electrophiles are of limited utility since allylic scrambling leading to homocoupling often occurs (Scheme 17). [8] Scheme 16 Couplings of Nickel–ð-Allyl Complexes with Alkyl, Alkenyl, and Aryl Halides [8] Br Ni Ni Br 28 + 2 R 1 X DMF Scheme 17 Potential Scrambling with Allylic Electrophiles [8] R2 R2 R Br Ni Ni Br 1 R 1 R 1 + R 2 R 3 R 2 In addition to the widely used couplings of alkyl, alkenyl, and aryl halides with ð-allyl complexes, couplings of nickel–ð-allyl complexes with aldehydes and ketones are also efficient. [35,41] Couplings involving the 3-bromo-2-methoxypropene derived complex 30 are particularly useful as a method for introducing the acetonyl functional group into organic substrates to give ketones such as 31 (Scheme 18). Scheme 18 The Use of a 3-Bromo-2-methoxypropene Derived Complex for the Introduction of the Acetonyl Functionality by Coupling with Iodobenzene [35,41] Br MeO Ni Ni OMe Br + PhI Br R 1 + DMF DMF 30 31 A <strong>detailed</strong> mechanistic study of the coupling of ð-allyl complexes and organic halides has been carried out. [42] A mechanism involving the establishment of a pre-equilibrium between bis(allyl)nickel complexes and monoallyl halo-bridged dimers is proposed. A single-electron-transfer mechanism then initiates cross coupling via nickel(I) intermediates. R 1 R 2 29 O R 1 R 3 Ph + R 3 R 3 for references see p 79
Page 1: Science of Synthesis Houben-Weyl Me
Page 8 and 9: 8 Science of Synthesis Category 1:
Page 11 and 12: Volume 1: Compounds withTransition
Page 13 and 14: Table of Contents Volume 2 13 Volum
Page 15 and 16: Table of Contents 15 Volume 4: Comp
Page 17 and 18: Table of Contents 17 4.4.27 Product
Page 23: Table of Contents 23 5.3.13 Product
Page 27 and 28: 2001 Georg Thieme Verlag Rüdigerst
Page 29 and 30: 1.1 Product Class 1: Organometallic
Page 31 and 32: 1.1 Product Class 1: Organometallic
Page 33 and 34: 1.1.1 Nickel Complexes of 1,3-Diene
Page 35 and 36: 1.1.1 Nickel Complexes of 1,3-Diene
Page 37 and 38: 1.1.2 Nickel-Allyl Complexes 37 tra
Page 39: 1.1.2 Nickel-Allyl Complexes 39 Bis
Page 43 and 44: 1.1.2 Nickel-Allyl Complexes 43 NiC
Page 45 and 46: 1.1.2 Nickel-Allyl Complexes 45 Sch
Page 47 and 48: 1.1.2 Nickel-Allyl Complexes 47 Sch
Page 49 and 50: 1.1.3 Nickel-Alkyne Complexes 49 Ca
Page 51 and 52: 1.1.3 Nickel-Alkyne Complexes 51 (2
Page 53 and 54: 1.1.3 Nickel-Alkyne Complexes 53 Sc
Page 55 and 56: 1.1.3 Nickel-Alkyne Complexes 55 at
Page 57 and 58: 1.1.3 Nickel-Alkyne Complexes 57 Sc
Page 59 and 60: 1.1.3 Nickel-Alkyne Complexes 59 en
Page 61 and 62: 1.1.3 Nickel-Alkyne Complexes 61 of
Page 63 and 64: 1.1.4 Nickel-Alkene Complexes 63 Bi
Page 65 and 66: 1.1.4 Nickel-Alkene Complexes 65 Sc
Page 67 and 68: 1.1.4 Nickel-Alkene Complexes 67 1.
Page 69 and 70: 1.1.4 Nickel-Alkene Complexes 69 Sc
Page 71 and 72: 1.1.4 Nickel-Alkene Complexes 71 [5
Page 75 and 76: 1.1.4 Nickel-Alkene Complexes 75 4-
Page 79 and 80: References 79 References [1] Chetcu
Page 81 and 82: References 81 [98] Tsuda, T.; Mizun
Page 86 and 87: 86 Biographical Sketches Rinaldo Po
Page 88 and 89: 88 2.6.4.2.2 Variation 2: Two-Elect
Page 90 and 91:
90 2.6 Product Class 6: Organometal
Page 92 and 93:
92 Science of Synthesis 2.6 Complex
Page 94 and 95:
Page 96 and 97:
Page 98 and 99:
Page 100 and 101:
100 Science of Synthesis 2.6 Comple
Page 102 and 103:
Page 104 and 105:
Page 106 and 107:
Page 108 and 109:
Page 110 and 111:
Page 112 and 113:
Page 114 and 115:
Page 116 and 117:
Page 118 and 119:
Page 120 and 121:
Page 122 and 123:
Page 124 and 125:
Page 126 and 127:
Page 128 and 129:
Page 130 and 131:
Page 132 and 133:
Page 134 and 135:
Page 136 and 137:
Page 138 and 139:
Page 141 and 142:
141 Science of Synthesis Houben-Wey
Page 143 and 144:
2002 Georg Thieme Verlag Rüdigerst
Page 145 and 146:
4.4.27 Product Subclass 27: Æ-Halo
Page 147 and 148:
4.4.27 Æ-Haloalkylsilanes 147 Sche
Page 149 and 150:
4.4.27 Æ-Haloalkylsilanes 149 dros
Page 151 and 152:
4.4.27 Æ-Haloalkylsilanes 151 4.4.
Page 153 and 154:
4.4.27 Æ-Haloalkylsilanes 153 In g
Page 155 and 156:
4.4.27 Æ-Haloalkylsilanes 155 4.4.
Page 157 and 158:
4.4.27 Æ-Haloalkylsilanes 157 Æ-H
Page 159 and 160:
References 159 References [1] Haman
Page 161:
References 161 [93] Bruno, J. W.; S
Page 164 and 165:
164
Page 166 and 167:
166 Biographical Sketches Alan Spiv
Page 168 and 169:
168 5.1.22 Product Subclass 22: Ary
Page 170 and 171:
170 Science of Synthesis 5.1 German
Page 172 and 173:
Page 174 and 175:
Page 176 and 177:
176 References [43] Eaborn, C.; Var
Page 178 and 179:
178 Abbreviations Chemical (cont.)
Page 180 and 181:
180 Abbreviations Ligands (cont.) 2
Page 182:
182 Abbreviations General (cont.) q
show all

ca01 only detailed ToC 1..24

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?