To provide a process for preparing the subject compound useful as an intermediate or the like for the preparation of amino acids, alkaloids, etc., by mixing an N-protected indoline with hydrogen or the like in the presence of a hydrogenation catalyst.
An N-protected indoline of formula I [R1 is a (non)substituted 2-10C alkenyl or a (non)substituted benzyl; R2 to R4 are each H, a halogen such as Br, a 1-7C alkyl, an aryl, a hydroxyl or the liked, (e.g. 5,6-dihydroxy-1- N-benzyloxycarbonylindoline) is stirred and mixed with hydrogen (at a low pressure of a molecular hydrogen) or a hydrogen-donor [e.g. an olefinic hydrogen donor such as a (substituted) cyclohexene and 1,3-cyclohexadiene] in the presence of a hydrogenation catalyst (palladium, Raney nickel or other metals of platinum group) at pH ≤7, preferably pH 5-7 under a temperature condition between the room temperature and a refluxing temperature of a reaction medium in a solvent to provide a compound of formula II (e.g. 5,6-dihydroxyindole) in the process for preparing the indole compound.
| WO/2013/095715 | ISOMERIZATION OF LIGHT PARAFFINS |
| WO/2009/079905 | A SELECTIVE HYDROGENATION CATALYST AND THE PREPARATION THEREOF |
| JP7395138 | hydrogenation electrocatalyst |
ERUBUEI BOROUIAAKU
ARAN RAGURANJI
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