Know the main synthetic routes and reactivity for furans, pyrroles and thiophenes thiophenes

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Heterocyclic and Pericyclic Chemistry Mapa Mental sobre Know the main synthetic routes and reactivity for furans, pyrroles and thiophenes thiophenes, creado por al44 el 05/12/2013.
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Resumen del Recurso

Know the main synthetic routes and reactivity for furans, pyrroles and thiophenes thiophenes
  1. Furans
    1. Synthesis
      1. Dehydrated 1,4 carbonyl compounds
        1. Carbonyls protonated
          1. Alcohol reacts with =O+H and a five membered ring forms with one alcohol group
            1. Loss of water, carbonyl acidified at beginning
      2. Source
        1. Carbohydrate waste
          1. Ribose/furanose structures
            1. furfural
              1. furan
        2. Reactivity
          1. Nitration
            1. Nitric acid and sulphuric acid
              1. polymeric resin
              2. Acetyl nitrate
                1. NO2 and AcO attached to 2 and 5 positions
                  1. OAc group lost when reacted with pyridine
              3. Bromination
                1. Br2, RT
                  1. Polybromination
                  2. Br2, dioxane
                    1. Br at 2 position
                    2. Br2, EtOH, -40oC
                      1. OEt at 2 and 5 position
                        1. Mechanism
                          1. monobromine sub
                            1. EtOH reacts at double bond adjacent to positive O atom
                              1. Loss of bromine atom
                                1. Addition of another EtOH group
                    3. Diels-Alder
                  3. Pyrroles
                    1. Synthesis
                      1. Paul Knorr
                        1. 1,4 dicarbonyl and amine
                          1. Mechanism
                            1. Addition of amine to C=O and protonation of C=O
                              1. Loss of water
                                1. Movement of double bond
                                  1. Ring closing
                                    1. Loss of water
                        2. Hantzsch
                          1. 1,4 dicarbonyl, haloketone and amine
                            1. Loss of water and HCl
                        3. Reactivity
                          1. Electrophilic substitution
                            1. v. reactive
                              1. 2, 3 posititons
                                1. Tetrabromination
                                2. Acid sensitive
                                  1. v. weak base
                                    1. lone pair on N used in 6 pi system
                                    2. Deprotection with base
                                      1. Can be alkylated at C or N
                                        1. Use alkyl halide
                                      2. Diels-Alder
                                        1. Needs N-EWG and highly reactive dienophile
                                    3. Thiophene
                                      1. Synthesis
                                        1. 1,4 dicarbonyl, P2S5, 170oC
                                          1. 1,3-diyne and metal sulphide, NaSH, EtOH
                                          2. Reactivity
                                            1. Electrophilic aromatic substitution
                                              1. Most aromatic of 3
                                              2. Not acid sensitive
                                                1. No diels alder
                                                  1. Friedel Crafts
                                                    1. Bromination at 2 position
                                                      1. Desulfurisation
                                                        1. Dehydrogenation carbon skeleton
                                                          1. Raney Nickel catalyst
                                                            1. Al/Ni alloy dissolved in aq. NaOH
                                                              1. Leaves sponge of fine particles with H2 absorbed
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