essay代写 > Chemistry essay 代写 > Moleculescontain the 1-azabicyclo[2.2.2]octan-2-one system代写

Moleculescontain the 1-azabicyclo[2.2.2]octan-2-one system代写

  • 100%原创,高质量代写&Turnitin反剽窃检测-24小时在线客服微信&QQ:273427
  •                  ANSWERS OF THOSE QUESTIONS
    1. Bicyclic lactams are of particular interest because of the structure of penicillin. Draw the contrasting models for the structures of penicillin proposed by Chain & Abraham /Woodward versus that proposed by Robertson. Give the evidence used by each proponent to support these different models.  15 marks
    For Chain & Abraham /Woodward

      From the results of salts and electrometric titration curves we get the conclusion that  it is strong monobasic acid and its pK’s index is about 2.9 . No evidence have shown that basic group in the electrotitration titration graph . We take it as a very important fact in structural considerations . If we imagine that the American penilloaldehyde contained a phenylacetyl group,  C6H5CH2CO·NH2·CHO would be its only structure . Suppose that our imagination is right , C5H9CONH·CH2·CHO would be the structure of C8 . The exist of Glycine in the acid was proved by its isolation in the form of the naphthalene-sulphony1 derivative . We suppose that its hydrolysis proceeded according to that equation while they get the news that American penicillin afford the same amino acid penicillamine on acid hydrolysis .Penicillin hydrolysis at 100℃ can get some nitrogen atoms and common acids, and analyzing the acid electrotitration curve ,we get the fact that penicillin is also a kind of acid . According to data shows, there is no evidence to suggest that the presence of any basic group in the electrotitration curve, in fact, the implementation of structural analysis provides important clues. Cracking occurs in strongly acidic conditions and generate penicillium acid and penicillium hyaluronic acid, penicillium hyaluronic acid is not stable .It will let out penicillium aldehyde . Side chain lone pair on the carbonyl O atom as nucleophilic reagent offensive beta lactam ring, generated intermediates, then through rearrangement generated penicillium diacid, generate penicillamine break down again . So its structure could beβ-Lactam Antibiotics . They proposed a penicillin in October 1943, the first full sense of the structure of the formula, of course, thanks to the tireless efforts of everyone at Oxford University. Regardless of their long talks.
    For Robertson :
      To support the structure of the experiment is the fact that penicillin product solutions of penicillium acid . Penicillium olefine acid can illustrate a Thiazole-Azole ketones penicillin
    Structure. So he thought the structural penicillin is Thiazole-Azole ketones constitutive.
    2. Explain the term “anti-Bredt” amides.  1 mark
    ANSWER :
      From these data , we think it is probable because the twisting phenomenon isn’t limited for cyclic systems. The non-planarity can be a decisive biological design element which alters the selectivity ,  mechanism and reactivity of various enzymatic and protein enzymatic processes and also result in amide ground-state destabilization .
      People acknowledge the properties of the twisted amides in 1938 . Molecules which contain the 1-azabicyclo[2.2.2]octan-2-one system are one of the simplest families.
    However , we do not distinctly synthesized part of this group named 2-quinuclidone .
    The data refer to the isolation ,characterization and synthesis of the HBF4 salt of 1 .
    The key point of the isolation and synthesis is that the route for generating 1 despite classical amide bond formation. They estimate the results can make us understand the qualities of amide bonds better .
    3. Explain the particular difficulty associated with isolating 1. 1 mark
    ANSWER :
      Using reactions which involves dinitrogen to release as a driving force for the construction of the strained bicyclic core is the core of the design for the synthesis of 1.This can potentially remove aqueous work-up circumstance during our last step .Two distinct routes are expected for the construction of the 1-azabicyclo[2.2.2]octane skeleton . We use acylcarbene chemistry for the construction of the C–N bond . Another way involves C–N bond formation by an intramolecular Schmidt–Aube´ reaction27 of cyclopentanone azide derivative 7 . Aube´reported the reaction in 1991 first and we use it to synthesis Figure 1 . The intramolecular amide bond formation can easily produce a structural isomer of 1.
    4. The text describes the 1-azabicyclo[2.2.2]octane skeleton for Quinuclidinone. Use this IUPAC nomenclature to describe the skeleton of the “constitutional isomer” in Figure 1b and give an example of how such isomers have been used for pharmaceutical applications. 1 mark
    ANSWER : NOMENCLATURE-----2-quinuclidinone
      We characterize the activation of the amino acid as the acid chloride only by elemental analysis for nitrogen and an aqueous work-up was reported to give 1.
    It is also a treatment with mild base.
    5. Draw mechanisms for ALL reactions given in the transformation of 9 into 16 and 17.Ensure that full structural formulae for reagents (e.g., m-CPBA, DMP, Ts), and protecting groups (e.g., BOC) are given.
    a. What would be the major side-products of the reactions used to prepare 10
    and 12? draw the mechanisms for their formation
    ANSWER :  For 10 :
             Mechanism :
                For 12 :
            Mechanism :
    b. Why was methanol added in the last step?
    Because the product is unstable for the lability of the amide , we use methanol to improve this condition .
    c. For each step suggest which method for visualising the thin layer
    chromatograms would have been used
    For 9-10 , we use the method Thin layer adsorption chromatography .
    For 11-12,we still use the method Thin layer adsorption chromatography .
    For 13-14 , we use the method Thin layer of gel chromatography .
    For 15-16 ,  we use the method Thin layer chromatography .
    d. Explain the methods used to isolate 10, 13, 16, 17 and 1.HBF4
    10 marks
    ANSWER : we use the method of extraction .Because they have different solubility in acetone . We use compounds in two types of mutually miscibility or slightly soluble solvent solubility and distribution coefficient is different, make the compounds from within a solvent to another solvent. After repeated extraction, to pick up the most of the compounds.
    6. Assign the spectra for 16 and 17. What piece of structural characterisation was the
    sole evidence for the enantiopurity of the product 1.HBF4.   2 marks
    ANSWER :
             1.2 ppm refers to the group : cycle
             7.2ppm refers to the group : CO2Me
             1.4 ppm refers to the group : carbonyl
    2 . carbonyl group
    The difference between 16 and 17 is that 17 has a -CH2that 16 do not have and this group may affect the graph of carbonyl . So we can guess that it is the carbonyl group that can prove it .

        (16)              (17)
    NOTE: for section 1, students will be required to submit an electronic copy with an
    appropriate turnitin score (details about this will be posted later)