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Chandrasekhar, S.; Basu, Debjit; Sailu, M.; Kotamraju, S. Novel synthetic route to the tricyclic core of ()-galanthamine. Tetrahedron Letters (2009), 50(34),

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Presentation on theme: "Chandrasekhar, S.; Basu, Debjit; Sailu, M.; Kotamraju, S. Novel synthetic route to the tricyclic core of ()-galanthamine. Tetrahedron Letters (2009), 50(34),"— Presentation transcript:

1 Chandrasekhar, S.; Basu, Debjit; Sailu, M.; Kotamraju, S. Novel synthetic route to the tricyclic core of ()-galanthamine. Tetrahedron Letters (2009), 50(34),

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5 pKa phenol = 9.9 pKa2 of carbonic acid = 10.33

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8 The Claisen Rearrangment is a [3,3] sigmatropic rearrangement Aromatic Claisen Rearrangement Cope Rearrangement is related

9 Sigmatropic: One sigma bond is changed to another.

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14 pKa conjugate acid of imidazole = 7.2

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16 DIPEA = Diisopropylethylamine (Hunig’s Base). This base is more sterically hindered, and thus less nucleophilic, than triethylamine. pKa of the conjugate acid of Hunig’s base = 11.0 MOM = Methoxymethyl MOMCl = H 3 C-O-CH 2 -Cl

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18 2,6-Lutidine = pKa conjugate acid of 2,6-lutidine = 6.7

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20 pKa hydroxylamine hydrochloride = 6 pKa conjugate acid of pyridine = 5.2 pKa conjugate acid of triethylamine = 10.6

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22 DMPU = Dimethylpropyleneurea = solvent to replace HMPA, a carcinogen LDA = lithium diisopropylamide pKa of diisopropylamine (conjugate acid of LDA) = 36 pKa acetonitrile = 25 pKa phenylacetonitrile = 22

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28 pKa p-toluenesulfonic acid = - 0.4

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38 DPPA = diphenylphosphoryl azide = DBU = Diazabicycloundecene = Conjugate acid of DBU pKa = 13.2

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