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Search for "ring strain" in Full Text gives 77 result(s) in Beilstein Journal of Organic Chemistry.
Mitomycins syntheses: a recent update
- Jean-Christophe Andrez
Beilstein J. Org. Chem. 2009, 5, No. 33, doi:10.3762/bjoc.5.33
- the “normal” 5-substituted isoxazoline is formed. Hence, the nitrodecene 123 gives rise to only the nine-membered carbocycle 125 upon reaction with phenyl isocyanate. The matching HOMO-LUMO interactions for such cycloadditions favour the formation of 126 but ring strain and transannular steric effects
Graphical Abstract
Scheme 1: Aziridine containing natural products.
Scheme 2: Mitomycin structures and nomenclature.
Scheme 3: Base catalysed epimerization of mitomycin B.
Scheme 4: Biosynthesis of mitomycin C (MMC) 7.
Scheme 5: Mode of action of mitomycin C.
Scheme 6: The N–C3–C9a disconnection.
Scheme 7: Danishefsky’s Retrosynthesis of mitomycin K.
Scheme 8: Hetero Diels–Alder reaction en route to mitomycins.
Scheme 9: Nitroso Diels–Alder cycloaddition.
Scheme 10: Frank azide cycloadddition.
Scheme 11: Final steps of mitomycin K synthesis. aPDC, DCM; bPhSCH2N3, PhH, 80 °C; cL-selectride, THF, −78 °C; ...
Scheme 12: Naruta–Maruyama retrosynthesis.
Scheme 13: Synthesis of a leucoaziridinomitosane by nitrene cycloaddition. aAlCl3-Et2O; bNaH, ClCH2OMe; cn-BuL...
Scheme 14: Thermal decomposition of azidoquinone 51.
Scheme 15: Diastereoselectivity during the cycloaddition.
Scheme 16: Oxidation with iodo-azide.
Scheme 17: Williams’ approach towards mitomycins.aDEIPSCl, Imidazole, DCM; bPd/C, HCO2NH4, MeOH; cAllocCl, NaH...
Scheme 18: Synthesis of pyrrolidones by homoconjugate addition.
Scheme 19: Homoconjugate addition on the fully functionalized substrate.
Scheme 20: Introduction of the olefin.
Scheme 21: Retrosynthesis of N–C9a, N–C3 bond formation.
Scheme 22: Synthesis of the pyrrolo[1,2]indole 82 using N-PSP activation.aAc2O, Py; bAc2O, Hg(OAc)2, AcOH, 90%...
Scheme 23: Synthesis of an aziridinomitosane. am-CPBA, DCM then iPr2NH, CCl4 reflux; bK2CO3, MeOH; cBnBr, KH; d...
Scheme 24: Oxidation products of a leucoaziridinomitosane obtained from a Polonovski oxidation.
Scheme 25: Polonovski oxidation of an aziridinomitosane. am-CPBA; bPd/C, H2; cDimethoxypropane, PPTS.
Scheme 26: The C1–C9a disconnection.
Scheme 27: Ziegler synthesis of desmethoxymitomycin A.aIm2C=O, THF; bNH3; cTMSOTf, 2,6-di-tert-butylpyridine, ...
Scheme 28: Transformation of sodium erythorbate.aTBDMSCl; bNaN3; cPPh3; d(Boc)2O, DMAP; eTBAF; fTf2O, Pyr.
Scheme 29: Formation of C9,C10-unsaturation in the mitomycins. am-CPBA, DCM; bO3, MeOH; cMe2S; dKHMDS, (EtO)3P...
Scheme 30: Fragmentation mechanism.
Scheme 31: Michael addition-cyclisation.
Scheme 32: SmI2 8-endo-dig cyclisation.
Scheme 33: Synthesis of pyrrolo[1,2-a]indole by 5-exo-dig radical cyclization.
Scheme 34: The C9–C9a disconnection.
Scheme 35: Intramolecular nitrile oxide cycloaddition.
Scheme 36: Regioselectivity of the INOC.
Scheme 37: Fukuyama’s INOC strategy.
Scheme 38: Synthesis of a mitosane core by rearrangement of a 1-(1-pyrrolidinyl)-1,3-butadiene.
Scheme 39: Sulikowski synthesis of an aziridinomitosene. aPd(Tol3P)2Cl2, Bu3SnF, 140; bH2, Pd/C; cTFAA, Et3N; d...
Scheme 40: Enantioselective carbene insertion.
Scheme 41: Parson’s radical cyclization.
Scheme 42: Cha’s mitomycin B core synthesis.
Scheme 43: The N-aromatic disconnection.
Scheme 44: Kishi retrosynthesis.
Scheme 45: Kishi synthesis of a starting material. aallyl bromide, K2CO3, acetone, reflux; bN,N-Dimethylanilin...
Scheme 46: Kishi synthesis of MMC 7. aLDA, THF, −78 °C then PhSeBr, THF, −78 °C; bH2O2, THF-EtOAc; cDIBAL, DCM...
Scheme 47: Acid catalyzed degradation of MMC 7.
Scheme 48: In vivo formation of apomitomycin B.
Scheme 49: Advanced intermediate for apomitomycin B synthesis.
Scheme 50: Remers synthesis of a functionalized mitosene. aTMSCl, Et3N, ZnCl2 then NBS; bAcOK; cNH2OH; dPd/C, H...
Scheme 51: Coleman synthesis of desmethoxymitomycin A. aSnCl2, PhSH, Et3N, CH3CN; bClCO2Bn, Et3N; cPPh3, DIAD,...
Scheme 52: Transition state and pyrrolidine synthesis.
Scheme 53: Air oxidation of mitosanes and aziridinomitosanes.
Scheme 54: The C9-aromatic disconnection.
Scheme 55: Synthesis of the aziridine precursor. aLHMDS, THF; bNaOH; c(s)-α-Me-BnNH2, DCC, HOBT; dDIBAL; eK2CO3...
Scheme 56: Synthesis of 206 via enamine conjugate addition.
Scheme 57: Rapoport synthesis of an aziridinomitosene.
Scheme 58: One pot synthesis of a mitomycin analog.
Scheme 59: Synthesis of compound 218 via intramolecular Heck coupling. aEtMgCl, THF, then 220; bMsCl, Et3N; cN...
Scheme 60: Elaboration of indole 223. aEt3N, Ac2O; bAcOH; cSOCl2, Et3N; dNaN3, DMF; eH2SO4, THF; fK2CO3, MeOH; ...
Scheme 61: C9-C9a functionalization from indole.
Scheme 62: Synthesis of mitomycin K. a2 equiv. MoO5.HMPA, MeOH; bPPh3, Et3N, THF-H2O; cMeOTf, Py, DCM; dMe3SiCH...
Scheme 63: Configurational stability of mitomycin K derivatives.
Scheme 64: Epimerization of carbon C9a in compound 227b.
Scheme 65: Corey–Chaykovsky synthesis of indol 235.
Scheme 66: Cory intramolecular aza-Darzens reaction for the formation of aziridinomitosene 239.
Scheme 67: Jimenez synthesis of aziridinomitosene 242.
Scheme 68: Von Braun opening of indoline 244.
Scheme 69: C9a oxidation of an aziridinomitosane with DDQ/OsO4.
Scheme 70: Synthesis of epi-mitomycin K. aNaH, Me2SO4; bH2, Pd/C; cMitscher reagent [165]; d[(trimethylsilyl)methyl...
Scheme 71: Mitomycins rearrangement.
Scheme 72: Fukuyama’s retrosynthesis.
Scheme 73: [2+3] Cycloaddition en route to isomitomycin A. aToluene, 110 °C; bDIBAL, THF, −78 °C; cAc2O, Py.; d...
Scheme 74: Final steps of Fukuyama’s synthesis.
Scheme 75: “Crisscross annulation”.
Scheme 76: Synthesis of 274; the 8-membered ring 274 was made using a crisscross annulation. a20% Pd(OH)2/C, H2...
Scheme 77: Conformational analysis of compound 273 and 275.
Scheme 78: Synthesis of a mitomycin analog. aNa2S2O4, H2O, DCM; bBnBr (10 equiv), K2CO3, 18-crown-6 (cat.), TH...
Scheme 79: Vedejs retrosynthesis.
Scheme 80: Formation of the azomethine ylide.
Scheme 81: Vedejs second synthesis of an aziridinomitosene. aDIBAL; bTPAP, NMO; c287; dTBSCl, imidazole.
Scheme 82: Trityl deprotection and new aziridine protecting group 300.
Scheme 83: Ene reaction towards benzazocinones.
Scheme 84: Benzazocenols via homo-Brook rearrangement.
Scheme 85: Pt-catalyzed [3+2] cycloaddition.
Scheme 86: Carbonylative lactamization entry to benzazocenols. aZn(OTf)2, (+)-N-methylephedrine, Et3N, TMS-ace...
Scheme 87: 8 membered ring formation by RCM. aBOC2O, NaHCO3; bTBSCl, Imidazole, DMF; callyl bromide, NaH, DMF; ...
Scheme 88: Aziridinomitosene synthesis. aTMSN3; bTFA; cPOCl3, DMF; dNaClO2, NaH2PO4, 2-methyl-2-butene; eMeI, ...
Scheme 89: Metathesis from an indole.
Scheme 90: Synthesis of early biosynthetic intermediates of mitomycins.
Dimerization of propargyl and homopropargyl 6-azido- 6-deoxy- glycosides upon 1,3-dipolar cycloaddition
- Nikolas Pietrzik,
- Daniel Schmollinger and
- Thomas Ziegler
Beilstein J. Org. Chem. 2008, 4, No. 30, doi:10.3762/bjoc.4.30
- dimers, trimers and tetramers. α-Galactoside 4e did not give any isolable dimer 7e at all (cf. Table 1, entry 5). Similarly, α-glucoside 4c resulted in a lower yield of the corresponding dimer compared to β-glucoside 4a (cf. Table 1, entries 1 and 3). This may be attributed to a significant ring-strain
Graphical Abstract
Figure 1: Schematic representation of glycosylated building blocks for the combinatorial synthesis of glycope...
Scheme 1: Synthesis and reaction of compounds 4a and 4a'.
Scheme 2: Preparation of compounds 4a–g.
