Preparation of Alkyl-Substituted Indoles in the Benzene Portion. Part 6. Synthetic Procedure for 4-, 5-, 6-, or 7-Alkoxy- and Hydroxyindole Derivatives.
Preparation of Alkyl-Substituted Indoles in the Benzene Portion. Part 8. Improved Practical Synthesis of 4,4-Dialkoxy-1-(1-arylsulfonyl-3-pyrolyl)-1-butanone and 4-(1-Arylsulfonyl-3-pyrrolyl)-4-oxobutanal, and a Novel Synthetic Procedure for 4-Alkoxyindole Derivatives.
A new, short-step synthesis of a β-adrenergic blocking agent, pindolol, 1-(4-indolyloxy)-3-(2-propylamino)-2-propanol, is described. The acid-catalyzed indole cyclization reaction of 4-[1-(4-methylphenyl)sulfonyl-3-phrroly]-4-oxobutanal (14) in the presence of (±)-3-chloro-1, 2-propanediol (12) and (R)-1-O-[(4-methylphenyl)sulfonyl]glycerol (24) afforded (±)-1-chloro-3-[1-(4-methylphenyl)sulfonyl-4-indolyloxy]-2-propanol (15) and (R)-(-)-3-[1-(4-methyl-phenyl)sulfonyl-4-indolyloxy]-1-[(4-methylphenyl)sulfonyloxy]-2-propanol (25). Reaction of these with isoproplamine and removal of the protecting group at the indole nitrogen gave (±)- and (S)-(-)-pindolol (3 and 4), thus constituting an efficient three-step synthesis of 3 and 4 from the readily available aldehyde (14).
描述了一种新的短步合成β-肾上腺素能阻断剂心得安(1-(4-吲哚氧基)-3-(2-丙胺基)-2-丙醇)的方法。在酸催化下,4-[1-(4-甲基苯基)磺酰-3-吡咯基]-4-氧丁醛(14)与(±)-3-氯-1,2-丙二醇(12)和(R)-1-O-[(4-甲基苯基)磺酰]甘油(24)反应,得到(±)-1-氯-3-[1-(4-甲基苯基)磺酰-4-吲哚氧基]-2-丙醇(15)和(R)-(-)-3-[1-(4-甲基苯基)磺酰-4-吲哚氧基]-1-[(4-甲基苯基)磺酰氧基]-2-丙醇(25)。这些化合物与异丙胺反应并除去吲哚氮上的保护基团,得到了(±)-和(S)-(-)-心得安(3和4),从而构成了从 readily available aldehyde (14)出发的高效三步合成的3和4的合成方法。
Preparation of Alkyl-Substituted Indoles in the Benzene Portion. Part 8. Improved Practical Synthesis of 4,4-Dialkoxy-1-(1-arylsulfonyl-3-pyrolyl)-1-butanone and 4-(1-Arylsulfonyl-3-pyrrolyl)-4-oxobutanal, and a Novel Synthetic Procedure for 4-Alkoxyindole Derivatives.
Important precursors (1 and 2) for the synthesis of 4-substituted indole derivatives were readily obtained by acid treatment of a tosylamide (13), which was prepared in a single operation by treatment of 10 with N-tosyl-N', N'-dimethylformamidine (TsN=CHNMe2). Compound (10) was effectively synthesezed from nitromethane and acrolein by way of a nitro compound (15). A novel indole formation reaction from the tosyl-amide (13) to gain short access to 4-alkoxyindoles, such as 16, 17, 19, and 21 is presented.
Preparation of Alkyl-Substituted Indoles in the Benzene Portion. Part 6. Synthetic Procedure for 4-, 5-, 6-, or 7-Alkoxy- and Hydroxyindole Derivatives.
A novel method for the preparation of indole derivatives that are alkoxy- and hydroxy-substituted in the benzene portion of the indole nucleus is described. The acid-induced cyclization reaction of (arylsulfonyl)pyrrole derivatives (4a, 5b, and 5a) in the presence of an appropriate alcohol gave 4-, 5-, 6-, and 7-alkoxyindole derivatives (13 and 28), respectively, where the alkoxy group was originated from the alcohol employed. As an application of the present method, a short and efficient synthesis of two dopamine agonists (34 and 44) was attained by treating appropriately functionalized pyrrole derivatives (38 and 41) with an acid in the presence of 1, 3-propanediol, followed by deprotection of alkoxy function, and subsequent reduction with lithium aluminum hydride. A reaction mechanism is also suggested for the formation of an unusual product, 4-[2-(diprophlamino)-1-hydroyethyl]-6-hydroxyindole (46) in the reduction of N, N-dipropyl-(6-hydroxy-1-phenylsulfonyl)indole-4-acetamide (40).