Synthetic methods in organic and supramolecular chemistry
by Colleen Nicola Scott
IN: 0542312042
Publisher: ProQuest / UMI - 20 March, 2006
Format: Paperback
List price: USD 69.99
The synthesis of cyclophane 17 (9,10,11,12,26,27,28,29-octahydro-3H,8H,16H,20H,25H,33H-4,7:21,24-dimethen-13,19,15:30,2,32-di[1]propane[1]yl[3]ylidine-1H,18H-dipyrimidino [1,2-a;1',6'-o] [1,8,15,22]tetraazacyclo-octacosine) is described. Both isomers of cyclophane 17 were synthesized over nine steps in 46% overall yield from readily available starting materials. We designed and synthesized a side group for attachment to cyclophane 17, which we wish to use for the directed-complexation of the cyclophane with a specified aromatic guest. We had hoped to use the Buchwald-Hartwig reaction to attach this side arm to the secondary amines of 17, but despite our many efforts we were unable to achieve this goal in a reproducible manner.* We have developed a method which allows the stepwise construction of silyl ketals; silyl ketals may be used as reactive intermediates in the construction of complex molecules. We synthesized silyl ketals 3a - 3i, 5a - 5f and 7a - 7e in moderate to high yields using a combination of Rh2(OAc) 4 followed by 10% Pd/C or Mn(CO)5Br as catalysts. We have shown that diisopropylsilane was crucial to the success of this process and that employing (+)-ethyl lactate as the alcohol in the first step leads to a faster and more efficient reaction in the second step. Silyl ketals 7a, 7b and 7d were used to show that intramolecular radical translocation beyond the 1,5 atom was not only feasible, but efficient.* *Please refer to dissertation for diagrams.
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