LOGIN TO YOUR ACCOUNT

Username
Password
Remember Me
Or use your Academic/Social account:

Congratulations!

You have just completed your registration at OpenAire.

Before you can login to the site, you will need to activate your account. An e-mail will be sent to you with the proper instructions.

Important!

Please note that this site is currently undergoing Beta testing.
Any new content you create is not guaranteed to be present to the final version of the site upon release.

Thank you for your patience,
OpenAire Dev Team.

Close This Message

CREATE AN ACCOUNT

Name:
Username:
Password:
Verify Password:
E-mail:
Verify E-mail:
*All Fields Are Required.
Please Verify You Are Human:

OpenAIRE is about to release its new face with lots of new content and services.
During September, you may notice downtime in services, while some functionalities (e.g. user registration, login, validation, claiming) will be temporarily disabled.
We apologize for the inconvenience, please stay tuned!
For further information please contact helpdesk[at]openaire.eu

fbtwitterlinkedinvimeoflicker grey 14rssslideshare1
Begbie, Alexander Lovelace
Languages: English
Types: Doctoral thesis
Subjects: QD
A possible synthetic route to vitamin B12 , proposed by J. W. Cornforth, is discussed in the Introduction, which also briefly gives the present status of other synthetic routes to corrins and to vitamin B12 In Cornforth's approach, precursors of ring A and ring D of vitamin B12 are to be linked together directly by an adaptation of a bromo-nitro coupling reaction and the work described in Chapters 1, 2, 3 and 4 deals with attempts to achieve this coupling and related work.\ud \ud A new synthetic route to Hagemann's ester (4-carbethoxy-3 -methyl- cyclohex-2-ene-1-one), which makes available the t-butyl ester as well as the methyl and ethyl ester in improved yield, has been discovered and is discussed in Chapter 1 with some mechanistic detail. The t-butyl ester adds nitroethane (as do the other esters) in the presence of a Triton base to give a nitro -ester which can be readily hydrolysed to the nitro –acid.\ud \ud The nitro-ester, derived by addition of nitro ethane to ethyl-Hagemann's ester, is shown (Chapter 2) to consist of the two epimers of trans-4-carbethoxy- 3 (methyl, 2-nitroethyl)-cyclohexanone by a degradative sequence involving a Nef reaction followed by a hypobromite oxidation. The product is then related to the known trans-4-carbomethoxy-3 (methyl, carbomethoxy)- cyclohexanone. The nitro-adducts thus have the correct ring stereochemistry for further development into vitamin B12 , This degradation can also be used for correlation of the enantiomers of the nitro ..acid after resolution.\ud \ud The nitro-ethyl ester epimers are converted (Chapter 3) into a single bromo-isomer (trans-4-carbethoxy-3 (methyl, 2,2-bromonitro-ethyl)- cyclohexanone and a coupling reaction with a primary nitro-anion is described, The failure of this reaction to give coupled products leads to the protection of the ketone in the nitro -ethyl ester with an ethylene -ketal followed by conversion into a single bromo -isomer , This compound also failed in the coupling reaction. The production of a single bromo-isomer from two epimers has important implications and hence a series of acid quenching of nitroanions is studied. These show remarkable stereo selectivity and several novel mechanistic features are discussed.\ud \ud The stereochemistry of a possible ring D precursor had not been determined in its entirety and Chapter 4 shows how the problems can be resolved although only the initial stages have been achieved.\ud
  • The results below are discovered through our pilot algorithms. Let us know how we are doing!

    • E. L. Rickes, N. G. Brink, F. R. Koniusky, T. R. Wood and K. Folkers, Science, 1948, 107, 396; E. Lester-Smith, Nature, 1949, -162, 144.
    • D. C. Hodgkin, J. Kamiper, J. Lindsey, M. Mackay, J. Pickworth, J. H. Robertson, G. B. Shoemaker, J. G. White, R. J. Prosen and K. N. Trueblood, Proc ,Roy. Soc,; -A, 1957, -242, 228.
    • H. A. Barker, H. Weissbach and R. D. Smyth, Proc.Nat.Acad.Sci., U.S.A., 1958, ~. 1093.
    • P. G. Lenhert and D. C. Hodgkin, Nature, 1961, 192, 937.
    • O. Millier andG. Milller, Biochem.j ,; 1962, 336,299; E. L. Smith, L. Merwin, A. W. JohnsonandN. Shaw, Nature, 1962, 194,1175; K. Bernhaller, O. Millier and G. Milller, Btochem.},; 1962, 336, 102; A. W. Johnson, N. Shaw and E. L. Smith, J. Chern. Soc., 1963, 4146.
    • W. Friedrich, G. Gross, K. BemhaUer and P. Teller, Helv. Chim. Acta, 1960, £. 704.
    • R. Bonnett,V. M. Clark, A. Giddey and A. Todd, J. Chern. Soc., 1959, 2087 and subsequent papers.
    • E. BerteIe, H. Boos, J. D. Dunttz, F. EIsinger, A. Eschenmoser, 1. Felne r, H. P. Gribi, H. Gschwend, E. F. Meyer, M. Pesaro and R. Scheffold, Angew,Chern. lntemat, Edn., 1964, ~ 490.
    • A. Eschenmoser, R. Scheffold, E. Bertele, M. Pesaro and H. Gschwend, Proc •Roy. Soc,; !!, 1965, ~ 306.
    • 1. Felner,A. Fischli, A. Wick, M Pesaro, D. Bormann, E. L. Winnacker and A. Eschenmoser, Angew.Chem.Intemat. Edn., 1967, ~ 864.
    • A. W. Johnson, Chern. in Britain, 1967, 253.
    • R. L. N. Harris, A. W. Johnson and I. T. Kay, Chem.Comm., 1965,355.
    • D. Dolphin, R. L. N. Harris, J. Huppatz, A. W. Johnson and I. T. Kay, J.Chem.Soc., f, 1966, 30.
    • A. W. Johnson and I. T. Kay, J.Chem.Soc., 1965, 1620.
    • D. Dolphin, A. W. Johnson, J. Leng and P. vanden Broek, J.Chem.Soc.,f, 1966, 880.
    • E. Bullock, A. W. Johnson, E. Markham andK. B. Shaw, J.Chem.Soc., 1958, 1430; J. H. Mathewson and A. H. Corwin, J.Amer .Chem .Soc , , 1961, ~ 135.
    • Y.Yamada, D. MUjkovic, P. Wehrli, B. Golding, P. Ldliger, R. Keese, K. MUller andA. Eschenmoser, Angew.Chem.lnternat.Edn., 1969, 8, 343.
    • R. B. Woodward and R. Hoffmann, Angew. Chem.Intemat.Edn., 1969, ~ 781.
    • A. Fischli and A. Eschenmoser, Angew.Chern. Internat, Edn., 1967, 2_, 866.
    • H. Heneka, Chem.Ber., 1948, ~ N. C. Ross and R. Levine, J.Org.Chem., 1964, !2_, 2346.
    • D. W. Mathieson, "Nuclear Magnetic Resonance for Organic Chemists, " Academic Press, London, 1967, p.232.
    • E. Toromanoff, "Topics in Stereochemistry, Vo1.2", edited by N. L, Allinger and E. L. EUel, Interscience, 1967, p.157.
    • E. Buchtaand G. Satzinger, Chern.Ber., 1959, ~ N. H. Anderson, M. McMillan and R, O. C. Norman, J.Chem.Soc., ~ 1970,1075; D. J. Edge, R. O. C. NormanandP. M. Storey, J.Chem.Soc., ~ 1970, 1096.
    • H. Schechter and R, B. Kaplan, J. Amer •Chern.Soc,; 1953, Z§.. 3980.
    • C. T. Bahner, U.S. patent 2,485,803 (1949).
    • N. Kornblum and G. E. Graham, J .Amer.Chem.Soc., 1951, ~ 4041.
    • A. A. Griswold and P. S. Starcher, J.Org.Chem., 1965, ~ 1687.
    • J. W. ApSimon, P. V. Demarco and D. W. Mathieson, Tetrahedron, 1970, ~ 119.
    • D. H. Williams and 1. Fleming, "Spectroscopic Methods in Organic Chemistry, "MCGraw-Hill, England, 1966, p.104.
    • R. A. Bell andE. N. C. Osakwe, Chem.Comm., 1968, 1093 and references therein.
    • M. F. Hawthorne, J .Amer. Chern.Soc., 1957, 7.2.t 2510.
    • V. Meyer and C. Wurster, Chem.Ber , , 1873, 6, 1168; M. J. Kamlet, L. A. Kaplan and }, C. Dacons, J.Org.Chem.,-1961, ~ 4371.
    • J. M. Brown, Ph.D. Thesis, University of Manchester, 1963; A. J. Birch, J. M. H. Graves and F. Stansfield, Proc , Chern.Soc. , 1962, 282.
    • A. J. Birch, H. SmithandR. E. Thornton, J.Chem.Soc., 1957, 1339; G. Stork and S, D. Darling, J.Amer.Chem.Soc., 1960, 82, 1512; 1964, ~ 1761. - W. D. Emmons, J.Amer, Chem.Soc ,; 1954, '!.2.! 3468, 3470.
    • L. F. Fieser and M. Fieser "Reagents for Organic Synthesis, " Wiley, New York, 196 , p.698.
    • A. I. Vogel, "Practical Organic Chemistry, " Longmans, London, 1948, p.971.
  • No related research data.
  • No similar publications.

Share - Bookmark

Cite this article

Cookies make it easier for us to provide you with our services. With the usage of our services you permit us to use cookies.
More information Ok