Download (3249Kb) - D-Scholarship@Pitt - University of Pittsburgh

More documents

Recommendations

Info

The transformation of ene-allene 75a to tetrahydroazepine 189 represents a formal intramolecular ene-reaction of type III (Scheme 3.44). 130 This type is characterized by terminal placement of the double bond in the “ene” unit, thereby leading to formation of the largest ring possible (191 to 192). Scheme 3.44 Type III intramolecular ene reaction. Type III intramolecular ene reaction Z H ∆ Z H 191 192 O O H b H a S 350 o C ~100% 193 194 FVP 500 o C 60% O O 196 197 There are only a few examples of type III ene reactions and these generally require very high temperatures to occur. For example, the thermal rearrangement of ortho-allylbutenyl benzene 193 occurs at 350 °C to give a mixture of fused benzocyclononadienes 194 and 195 in quantitative yield. 131 Similarly, thioaldehyde 196 undergoes an intramolecular ene reaction under flash vacuum pyrolysis (FVP) at 500 °C affording a thialactone 197, in a rare example of 7- membered ring formation. 132 The high temperature required for this reaction to occur can be attributed to the strained nature of the transition state 198 required for an ene reaction. Therefore, the formation of tetrahydroazepine 189 via a Rh(I)-catalyzed cycloisomerization reaction of 75a at 90 °C is an intriguing result. Moreover, azepines are an important synthetic target due to their presence in a variety of natural products (cephalotaxanes, Stemona and Securinega alkaloids, 133, 134 Figure 3.4). 74 H a S H b + H H H b 195 S 198 O O H a
Figure 3.4 Examples of natural products containing an azepine ring. O O HO H N OMe cephalotaxine (cephalotaxane alkaloid) O Me O H H H Et H H N stenine (Stemona alkaloid) O O H N securinine (Securinega alkaloid) At least two mechanistic pathways can be proposed for the cycloisomerization reaction of ene-allene 75a to azepine 189 (Scheme 3.45). Path A involves oxidative insertion of Rh(I) between the alkene and the proximal double bond of the allene, in an endo mode, affording a Rh(III) bridging metallocycle 200. Extraction of Ha via a β-hydride elimination would lead to Rh(III)-hydride species 201, which then undergoes a reductive elimination to afford the observed product 189. Scheme 3.45 Proposed mechanisms of the Rh(I)-catalyzed cycloisomerization of ene-allene 75a. Bz MeO2C Bn Hb N H Me Ha Me 189 H b BzN H a H 203 C RhL n H H E Me Me H BzN Rh(I)Ln Path B "Rh π-allyl mechanism" Ha RhLn Hb H 202 Me H • Me Hb BzN LnRh Ha D H Me H H • Me H Rh(I)L n Path A "Rh-metallocycle mechanism" H b BzN A LnRh Ha H H B Hb Me BzN H H Me A: oxidative addition; B: β-hydride elimination; C: reductive elimination; D: C-H insertion; E: carbometallation. Note: The 2-carbomethoxy and 2-benzyl substituents were omitted in the mechanism for clarity purposes. Me Bz N • MeO2C Bn 199 75 75a [Rh(CO) 2Cl] 2 200 H a H Hb Bz N MeO2C C Bn Ha RhL n H H 201 Me Me 189 H Me H Me
Page 1 and 2:
TRANSITION METAL-CATALYZED REACTION
Page 3 and 4:
Transition Metal-Catalyzed Reaction
Page 5 and 6:
List of Abbreviations Ac acetyl AcO
Page 7 and 8:
Table of Contents 1.0 Introduction.
Page 9 and 10:
Appendix A : X-ray crystal structur
Page 11 and 12:
Table 4.8 Rh(I)-catalyzed cyclocarb
Page 13 and 14:
List of Schemes Scheme 1.1 Three fo
Page 15 and 16:
Scheme 3.24 Preparation of amide-te
Page 17 and 18:
Scheme 4.16 Formation of bicyclo[5.
Page 19 and 20:
1.0 Introduction 1.1 The Role of Di
Page 21 and 22:
According to these guidelines, the
Page 23 and 24:
Scheme 1.1 Three forms of diversity
Page 25 and 26:
Another example from the Schreiber
Page 27 and 28:
1.1.1 Transition Metal-Catalyzed Re
Page 29 and 30:
37, , such reactions include transi
Page 31 and 32:
the proximal olefin of allenyne 38
Page 33 and 34:
2.0 Design and Synthesis of the Piv
Page 35 and 36:
The allenic amino acid derivatives
Page 37 and 38:
This protocol proved particularly u
Page 39 and 40:
ZnCl2, which results in a Zn-chelat
Page 41 and 42: Scheme 2.7 Synthesis of trisubstitu
Page 43 and 44: THF), the yield was increased from
Page 45 and 46: the terminus of the alkyne led to d
Page 47 and 48: N-Alkylation of the glycine-derived
Page 49 and 50: circumvent this issue, variants suc
Page 51 and 52: BINAP as a chiral ligand to obtain
Page 53 and 54: stereochemistry of the exocyclic ol
Page 55 and 56: 3.2 Rhodium(I)-Catalyzed Allenic Cy
Page 57 and 58: exocyclic olefin geometry is not re
Page 59 and 60: 3.2.1 Preparation of Enol-ether Tri
Page 61 and 62: Scheme 3.15 Synthesis of cycloisome
Page 63 and 64: Scheme 3.17 Cycloisomerization of a
Page 65 and 66: Scheme 3.19 Tandem cycloadditions o
Page 67 and 68: Scheme 3.21 Intermolecular Diels-Al
Page 69 and 70: attractive, since additional functi
Page 71 and 72: increased yield of the triene (47%)
Page 73 and 74: as an isobutyl-amide 155b was prepa
Page 75 and 76: group) demonstrated that this cyclo
Page 77 and 78: in 1M HCl/dioxane (1 : 1) for 1h, t
Page 79 and 80: ppm (dd, J = 7.1, 4.6 Hz, 1H) assig
Page 81 and 82: http://ccc.chem.pitt.edu/). Using f
Page 83 and 84: Notably, exclusive cycloisomerizati
Page 85 and 86: intermediate in the reaction we sou
Page 87 and 88: epulsive dipole interactions (Schem
Page 89 and 90: Table 3.4 Diels-Alder reactions of
Page 91: allenic Alder-ene reaction, ene-all
Page 95 and 96: species onto the proximal double bo
Page 97 and 98: Scheme 3.49 Rh(I)-catalyzed ene rea
Page 99 and 100: y Magnus 144 and it involves the in
Page 101 and 102: usually is DMSO. Heating to 100 ºC
Page 103 and 104: that require high pressures of CO.
Page 105 and 106: In contrast to the Mo(CO)6-mediated
Page 107 and 108: Scheme 4.15 Rh(I)-catalyzed allenic
Page 109 and 110: 4.2 Rhodium(I)-Catalyzed Cyclocarbo
Page 111 and 112: lack of double bond selectivity, si
Page 113 and 114: Table 4.2 Cyclocarbonylation reacti
Page 115 and 116: Notably, the allenic cyclocarbonyla
Page 117 and 118: Scheme 4.22 Cyclocarbonylation reac
Page 119 and 120: neat or in solution. This decomposi
Page 121 and 122: the newly synthesized fulvenes (e.g
Page 123 and 124: stereocenters and mixture of E/Z is
Page 125 and 126: proximal double bond to give α-alk
Page 127 and 128: the methyl ester and Ha are syn. Sc
Page 129 and 130: that the major diastereomer in the
Page 131 and 132: We were motivated to first examine
Page 133 and 134: Scheme 4.42 Synthesis of pyrrole 29
Page 135 and 136: periodic acid (H5IO6). 209 These hi
Page 137 and 138: eaction failed to go to completion,
Page 139 and 140: 4.5.2 Synthesis of a Library of Tri
Page 141 and 142: diketones 312{1-3,1-2} in yields ra
Page 143 and 144:
Figure 4.2 Distribution for physico
Page 145 and 146:
tricyclic pyrrole 314{3,2,26} (Figu
Page 147 and 148:
4.6 Synthesis of α-Alkylidene Cycl
Page 149 and 150:
anched and linear carboxylic acid i
Page 151 and 152:
eactivity of the species prepared i
Page 153 and 154:
considerably lower than the ratio o
Page 155 and 156:
diastereomer. Next, allenyne 328 wa
Page 157 and 158:
Conclusions In summary, we have dem
Page 159 and 160:
Experimental Section General Method
Page 161 and 162:
General procedure A for esterificat
Page 163 and 164:
F Bz N H 56f 2-Benzoylamino-3-(4-fl
Page 165 and 166:
MeO2C Bz N H 58c 2-Benzoylamino-2-m
Page 167 and 168:
MeO MeO2C Bz N H 58e 2-Benzoylamino
Page 169 and 170:
mL) and MeOH (10 mL) instead of sat
Page 171 and 172:
hexanes-EtOAc, 19 : 1 to 4 : 1, v/v
Page 173 and 174:
which was immediately used in the C
Page 175 and 176:
Boc TMS N H Bn 64f tert-Butyl-1-((4
Page 177 and 178:
MeI (38 µL, 0.62 mmol). Yield 65a
Page 179 and 180:
with brine and concentrated under v
Page 181 and 182:
H MeO 2C • H Bn NHBoc tert-Butyl-
Page 183 and 184:
TMS MeO 2C • 70 H H NHBoc 2-tert-
Page 185 and 186:
185 (10), 141 (21), 57 (100); EI-HR
Page 187 and 188:
dispersion in mineral oil, 1.0 mmol
Page 189 and 190:
EI-HRMS calcd for C30H26NO3 m/z [M-
Page 191 and 192:
CbzN MeO 2C Me 73h 2-[Benzyloxycarb
Page 193 and 194:
CbzN MeO 2C Me 2-(Benzyloxycarbonyl
Page 195 and 196:
dispersion in mineral oil, 3.85 mmo
Page 197 and 198:
completion of the addition, the rea
Page 199 and 200:
BzN MeO 2C S 74h 2-(Benzoylprop-2-y
Page 201 and 202:
BzN MeO 2C Bn 75b 2-(Allylbenzoylam
Page 203 and 204:
BzN MeO 2C TBSO 75e 2-(Benzoylbut-2
Page 205 and 206:
Hz, 1H), 5.85 (s, 1H), 5.52 (dd, J
Page 207 and 208:
1H), 3.69 (s, 3H), 1.58 (d, J = 7.1
Page 209 and 210:
µmol), [Rh(CO)2Cl]2 (1 mg, 3 µmol
Page 211 and 212:
1.25 (m, 6H), 0.88 (t, J = 6.9 Hz,
Page 213 and 214:
6.72 (d, J = 7.6 Hz, 0.5H), 6.68 (d
Page 215 and 216:
BzN MeO2C Bn 122a Methyl-2-(N-(but-
Page 217 and 218:
Bz N MeO2C Bn 1-Benzoyl-2-benzyl-4-
Page 219 and 220:
13.9, 5.3 Hz, 1H), 2.51-2.47 (m, 1H
Page 221 and 222:
15 min the solvent was removed unde
Page 223 and 224:
Benzoyl chloride (0.169 mL, 1.46 mm
Page 225 and 226:
mg, 0.11 mmol), [Rh(CO)2Cl]2 (4 mg,
Page 227 and 228:
mL). kk The aqueous layer was extra
Page 229 and 230:
ºC. After quenching the reaction b
Page 231 and 232:
129.8, 129.0, 128.7, 128.4, 126.2,
Page 233 and 234:
MeO 2C O O O N H N R 1 O N Ph [10c-
Page 235 and 236:
The crude residue was purified by f
Page 237 and 238:
14.4 Hz, 1H), 3.49-3.39 (m, 2H), 3.
Page 239 and 240:
1H), 5.49 (dd, J = 17.3, 1.8 Hz, 1H
Page 241 and 242:
was stirred at rt for 1 h when it w
Page 243 and 244:
BzN HOOC 2-(N-(but-2-ynyl)benzamido
Page 245 and 246:
°C and DIBAL-H (0.440 mL of a 1.0M
Page 247 and 248:
129 (62), 91 (100); EI-HRMS calcula
Page 249 and 250:
(d, J = 18.0 Hz, 1H), 4.14 (d, J =
Page 251 and 252:
4.98 (dt, J = 7.7, 5.1 Hz, 1H), 4.1
Page 253 and 254:
N Bz MeO2C OTBS 214 1-Benzoyl-2-(te
Page 255 and 256:
270a (major diastereomer-eluting fi
Page 257 and 258:
CDCl3): δ 7.42-7.17 (m, 13H), 7.04
Page 259 and 260:
18.6 Hz, 1H), 4.34 (d, J = 18.0 Hz,
Page 261 and 262:
Bz N MeO2C 2-Benzoyl-3,7-dimethyl-6
Page 263 and 264:
v/v) afforded a mixture of compound
Page 265 and 266:
(435 mg, 1.21 mmol), DMSO (429 µL,
Page 267 and 268:
4.02 (s, 1H), 3.88 (s, 3H), 1.82 (s
Page 269 and 270:
(207 mg, 96%) consisting of 287e (7
Page 271 and 272:
procedure O, using: 74f (110 mg, 0.
Page 273 and 274:
Bz N O H CO2Me BocN 287i 3-(2-Benzo
Page 275 and 276:
4.17 (d, J = 15.0 Hz, 1H), 4.10 (d,
Page 277 and 278:
137.1, 136.9, 130.4, 129.8, 128.5,
Page 279 and 280:
H BzN MeO2C Bn H N C3H7 298b CO 2Me
Page 281 and 282:
NMR (75 MHz, CDCl3): δ 172.3, 169.
Page 283 and 284:
following the general procedure Q,
Page 285 and 286:
H BzN MeO2C Bn H 5-Benzoyl-1,4-dibe
Page 287 and 288:
119.9, 114.1, 109.9, 108.6, 73.0, 5
Page 289 and 290:
4.11 (m, 1H), 4.07-3.98 (m, 1H), 3.
Page 291 and 292:
126.8, 126.2, 109.0, 72.9, 58.7, 56
Page 293 and 294:
NMR (75 MHz, CDCl3): δ 172.2, 169.
Page 295 and 296:
3.0 Hz, 1H), 5.82-5.80 (m, 1H), 5.2
Page 297 and 298:
87%). The diastereomeric ratio (288
Page 299 and 300:
APPENDIX A: X-ray crystal structure
Page 301 and 302:
APPENDIX B: X-ray crystal structure
Page 303 and 304:
APPENDIX C: X-ray crystal structure
Page 305 and 306:
APPENDIX D: X-ray crystal structure
Page 307 and 308:
APPENDIX E: X-ray crystal structure
Page 309 and 310:
APPENDIX F: QikProp property predic
Page 311 and 312:
1 H and 13 C NMRs of 74b 293
Page 313 and 314:
1 H and 13 C NMRs of 111a 295
Page 315 and 316:
Page 317 and 318:
Page 319 and 320:
Page 321 and 322:
1 H and 13 C NMRs of 270h 303
Page 323 and 324:
Page 325 and 326:
1 H and 13 C NMRs of 307 307
Page 327 and 328:
1 H and 13 C NMRs of 308n 309
Page 329 and 330:
10. (a) Burke, M. D.; Schreiber, S.
Page 331 and 332:
Hu, Y. J. Comb. Chem. 2006, 8, 286.
Page 333 and 334:
49. For reviews on reactions of all
Page 335 and 336:
69. (a) Trost, B. M.; Lautens, M.;
Page 337 and 338:
containing cross-conjugated trienes
Page 339 and 340:
Vaillancourt, J.; Rasper, D. M.; Ta
Page 341 and 342:
130. Oppolzer, W.; Snieckus, V. Ang
Page 343 and 344:
149. (a) Hicks, F. A.; Buchwald, S.
Page 345 and 346:
Maiese, W. M. J. Antibiot. 2000, 53
Page 347 and 348:
192. The mechanism of decomposition
Page 349 and 350:
Boger, D. L.; Boyce, C. W.; Labroli
Page 351:
Generated Inhibitors of Human Mitog
show all

Download (3249Kb) - D-Scholarship@Pitt - University of Pittsburgh

Create successful ePaper yourself

Delete template?

Save as template?