| the original synth:::= To a 250ml 3 neck RBF fitted with thermometer, condenser and a stir bar there is added 3-(1-naphthoyl)indole (3g, 11mmol) followed by dry DMF 50ml. Potassium hydroxide flakes (1.5g, 27.5mmol 1.5eq.) were added in one portion and the setup purged with butane. The flask was heated to 60-70 degrees C on a water bath for 20 minutes with stirring. A green solution with ppt is obtained. After this time, 1-bromopentane (4.3g, 28.6mmol) was added in one portion via glass syringe.There is an immediate color change to red and the flask is heated at an internal temp of 60-65 C for 3 hours. KBr ppts in the first few minutes after addition of the alkyl halide. It is then cooled to RT and diluted with 150ml H2O, and extracted with DCM 3x 40ml. The organics are washed with water 3 times then the solvent is evaporated. There is excess bromopentane as noticed by the smell so it is removed under vacuum in a hot water bath.3g of amber oil was obtained (8.8mmol, 80% yield) The amber oil that remains is the product. It is a pain to get it to crystallize. Only after 1 month in the refrigerator did crystals begin to form. By covering them with a small amount of IPA cleaned them up and caused all of the oil to crystallize. Once you have a seed crystal the oil can be directly crystallized after alkylation, but I have had no luck getting it to crystallize right after without the seed or with ethanol.The obtained material is completely melted by 61 C, lit Mp is 60-62 C ... |
