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The scope of this transformation was next examined by varying different substituents on the allenyne. First, only allenynes substituted with a methyl group on the terminal allenic position were tested to avoid formation of E/Z isomers of the appending olefin. In all cases, the reaction proceeded in 10 min to afford the cross-conjugated trienes 111b-111i (Table 3.1). The reaction conditions were compatible with either a Bz- (entries 1-4) or Cbz- (entries 5-8) protected amine. Allenynes 73b and 73g with a terminal alkyne reacted to give 111b and 111g in 74% and 84% yield, respectively (entries 1 and 6). Substitution of the alkyne terminus with either a TMS (entries 2 and 7) or phenyl group (entries 3 and 8) resulted in the corresponding trienes in yields ranging between 81-95%. Finally, variations at the amino acid side chain R 1 with a methyl (entries 5-8), benzyl (entries 1-3) and silyloxymethylene (entry 4) group were also incorporated without event. Table 3.1 Allenic Alder-ene reaction affording cross-conjugated trienes. P N MeO 2C R 1 73b-i • R 2 H 5 mol % [Rh(CO) 2Cl] 2 toluene, rt, 10 min P N MeO2C R1 111b-i entry allenyne P R 1 R 2 triene yield% entry allenyne P R 1 R 2 triene yield% 1 73b Bz Bn H 111b 74 5 73f Cbz Me Me 111f 81 2 73c Bz Bn TMS 111c 92 6 73g Cbz Me H 111g 84 3 73d Bz Bn Ph 111d 81 7 73h Cbz Me TMS 111h 87 4 73e Bz -CH 2OTBS Me 111e 89 8 73i Cbz Me Ph 111i 95 It is noteworthy to mention that Bz-protected allenynes (73a-73e, entries 1-4 and Scheme 3.1) were subjected to the reaction conditions as mixtures of diastereomers (~1.7 : 1, see Chapter 2) while the Cbz-protected allenynes (entries 5-8) were nearly single isomers (all compounds are racemic; see Chapter 2 for preparation of allenic amino-esters). Nevertheless, all reactions resulted in the corresponding cross-conjugated triene as a single isomer indicating that the 38 R 2
exocyclic olefin geometry is not related to the relative stereochemistry of the allenyne, and is a result of the last reductive elimination step in the mechanism of the reaction. b It should be noted that the rate with which the reaction of these amino-ester tethered substrates proceeded was noticeably higher compared to previous examples reported by Brummond and coworkers, some of which required up to 6 h for completion. 77 That the increased reactivity of the amino-ester substrates is likely a result of a Thorpe-Ingold effect imposed by the quaternary center adjacent to the allene. 82 In addition, the carbomethoxy group may play a directing role by reversibly coordinating to the metal center. 83 Next, variations of the substituents on the allene moiety were tested (Scheme 3.12). Allenyne 73j, substituted with an isopropyl group at the terminal allenic position reacted to afford triene 111j with trisubstituted appending olefin in 95% yield. In this case, there is only one hydrogen atom that can undergo β-hydride elimination. This does not affect the rate or the yield of the reaction, since 111j was produced in 95% yield after 10 min. Scheme 3.12 Preparation of polysubstituted trienes 111j-111l. N R • 1 P R MeO2C 4 CHR2R3 H 5 mol % [Rh(CO) 2Cl] 2 toluene, rt, 10 min 73j (P = Cbz, R 1 = Me, R 2 = R 3 = Me, R 4 = H) 73k (P = Cbz, R 1 = Me, R 2 = R 3 = Me, R 4 = n-Bu) 73l (P = Boc, R 1 = Bn, R 2 = H, R 3 = C 5H 11, R 4 = Me) Cbz MeO 2C N Cbz MeO 2C N P N MeO2C R1 R4 R2 Boc MeO 2C 111j 95% 111k 78% 111l 80% (E isomer only) b For the proposed mechanism of the reaction, see Scheme 3.8. 39 N Bn R 3
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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: 3.2 Rhodium(I)-Catalyzed Allenic Cy
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 and 92: allenic Alder-ene reaction, ene-all
Page 93 and 94: Figure 3.4 Examples of natural prod
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
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4.2 Rhodium(I)-Catalyzed Cyclocarbo
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lack of double bond selectivity, si
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Table 4.2 Cyclocarbonylation reacti
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Notably, the allenic cyclocarbonyla
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Scheme 4.22 Cyclocarbonylation reac
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neat or in solution. This decomposi
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the newly synthesized fulvenes (e.g
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stereocenters and mixture of E/Z is
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proximal double bond to give α-alk
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the methyl ester and Ha are syn. Sc
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that the major diastereomer in the
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We were motivated to first examine
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Scheme 4.42 Synthesis of pyrrole 29
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periodic acid (H5IO6). 209 These hi
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eaction failed to go to completion,
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4.5.2 Synthesis of a Library of Tri
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diketones 312{1-3,1-2} in yields ra
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Figure 4.2 Distribution for physico
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tricyclic pyrrole 314{3,2,26} (Figu
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4.6 Synthesis of α-Alkylidene Cycl
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anched and linear carboxylic acid i
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eactivity of the species prepared i
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considerably lower than the ratio o
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diastereomer. Next, allenyne 328 wa
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Conclusions In summary, we have dem
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Experimental Section General Method
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General procedure A for esterificat
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F Bz N H 56f 2-Benzoylamino-3-(4-fl
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MeO2C Bz N H 58c 2-Benzoylamino-2-m
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MeO MeO2C Bz N H 58e 2-Benzoylamino
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mL) and MeOH (10 mL) instead of sat
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hexanes-EtOAc, 19 : 1 to 4 : 1, v/v
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which was immediately used in the C
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Boc TMS N H Bn 64f tert-Butyl-1-((4
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MeI (38 µL, 0.62 mmol). Yield 65a
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with brine and concentrated under v
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H MeO 2C • H Bn NHBoc tert-Butyl-
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TMS MeO 2C • 70 H H NHBoc 2-tert-
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185 (10), 141 (21), 57 (100); EI-HR
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dispersion in mineral oil, 1.0 mmol
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EI-HRMS calcd for C30H26NO3 m/z [M-
Page 191 and 192:
CbzN MeO 2C Me 73h 2-[Benzyloxycarb
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CbzN MeO 2C Me 2-(Benzyloxycarbonyl
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dispersion in mineral oil, 3.85 mmo
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completion of the addition, the rea
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BzN MeO 2C S 74h 2-(Benzoylprop-2-y
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BzN MeO 2C Bn 75b 2-(Allylbenzoylam
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BzN MeO 2C TBSO 75e 2-(Benzoylbut-2
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Hz, 1H), 5.85 (s, 1H), 5.52 (dd, J
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1H), 3.69 (s, 3H), 1.58 (d, J = 7.1
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µmol), [Rh(CO)2Cl]2 (1 mg, 3 µmol
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1.25 (m, 6H), 0.88 (t, J = 6.9 Hz,
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6.72 (d, J = 7.6 Hz, 0.5H), 6.68 (d
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BzN MeO2C Bn 122a Methyl-2-(N-(but-
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Bz N MeO2C Bn 1-Benzoyl-2-benzyl-4-
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13.9, 5.3 Hz, 1H), 2.51-2.47 (m, 1H
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15 min the solvent was removed unde
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Benzoyl chloride (0.169 mL, 1.46 mm
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mg, 0.11 mmol), [Rh(CO)2Cl]2 (4 mg,
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mL). kk The aqueous layer was extra
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ºC. After quenching the reaction b
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129.8, 129.0, 128.7, 128.4, 126.2,
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MeO 2C O O O N H N R 1 O N Ph [10c-
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The crude residue was purified by f
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14.4 Hz, 1H), 3.49-3.39 (m, 2H), 3.
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1H), 5.49 (dd, J = 17.3, 1.8 Hz, 1H
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was stirred at rt for 1 h when it w
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BzN HOOC 2-(N-(but-2-ynyl)benzamido
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°C and DIBAL-H (0.440 mL of a 1.0M
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129 (62), 91 (100); EI-HRMS calcula
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(d, J = 18.0 Hz, 1H), 4.14 (d, J =
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4.98 (dt, J = 7.7, 5.1 Hz, 1H), 4.1
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N Bz MeO2C OTBS 214 1-Benzoyl-2-(te
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270a (major diastereomer-eluting fi
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CDCl3): δ 7.42-7.17 (m, 13H), 7.04
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18.6 Hz, 1H), 4.34 (d, J = 18.0 Hz,
Page 261 and 262:
Bz N MeO2C 2-Benzoyl-3,7-dimethyl-6
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v/v) afforded a mixture of compound
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(435 mg, 1.21 mmol), DMSO (429 µL,
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4.02 (s, 1H), 3.88 (s, 3H), 1.82 (s
Page 269 and 270:
(207 mg, 96%) consisting of 287e (7
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procedure O, using: 74f (110 mg, 0.
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Bz N O H CO2Me BocN 287i 3-(2-Benzo
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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
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NMR (75 MHz, CDCl3): δ 172.3, 169.
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following the general procedure Q,
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H BzN MeO2C Bn H 5-Benzoyl-1,4-dibe
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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.
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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
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