No abstract

Three practical synthetic entries of functionalized 6‐fluoro‐7‐substituted indole derivatives were developed in connection with the preparation of 7‐fluoro‐8‐substituted‐1,3,4,9‐tetrahydropyrano[3,4‐b]indole‐1‐acetic acid derivatives 11. The first route, which permits group modification about position 8 of the pyranoindole skeleton, employs 2‐bromo‐3‐fluoroaniline (18) as a key intermediate, the preparation of which was achieved by either a novel ortho metalation of 15 or via the intermediacy of 22. The second route utilizes 32 to append a terminally functionalized three carbon side chain onto the indole template and in addition leads to 43 from 40. The third route to the 7‐fluoro‐8‐substituted‐pyranoindole skeleton complements route two in that the synthetic pathway exploits 32 in a nucleophilic fashion to construct a terminally functionalized two carbon appendage onto the indole nucleus.

The synthesis of cis-1-ethyl-1,3,4,9-tetrahydro-4-(phenylmethyl)pyrano[3,4-b]indole -1-acetic acid, pemedolac (USAN), is described. This compound has been found to be a potent analgesic agent in primary screening. Pemedolac has been resolved and the active (+)-enantiomer assigned a 1S,4R absolute configuration on the basis of a crystallographic analysis of its (S)-(-)-borneol ester.

206 ChemInform Abstract Several methods of preparing the title compound (X) from indole derivatives are described. One key intermediate is the (hydroxymethyl)phenylethylindole (IV) which is obtained from isatin (I) and the phenylpropionate (II) or from the indolylacetate (V) and benzyl chloride (VI). (IV) undergoes cyclocondensation with the methoxypentenoate (VIII), forming the dihydropyranoindolylacetates (IX). Saponification of the main diastereomer (IXa) yields pemedolac (X). An alternative pathway to (IX) starts with the oxime (XI) which is hydrogenated and reduced, giving the amino alcohol (XII). This is N-protected and then cyclized with (VIII), producing the fused aminodihydropyran derivative (XV) which is subjected to a complex formylation, dehydration, cleavage, and rearrangement procedure, followed by coupling with benzylmagnesium bromide (XVII), to yield (IX). Pemedolac (X) has analgesic activities. (X-ray analysis of (X) and its (S)-borneol ester).

The synthesis of 5-[hydroxy-2-[(1-methyl-3-phenylpropyl)amino]ethyl]-1H-indole-7- carboxamide, 5, a pyrrolo analogue of labetalol, is described. Compound 5 was found to reduce blood pressure in spontaneously hypertensive rats with an ED50 of 5 mg/kg po, without causing any decrease in heart rate. Isolated tissue studies with 5 shows that it is a nonselective beta-adrenoceptor antagonist and that it is a weaker alpha-adrenoceptor antagonist with a relative selectivity for alpha 1-receptors. Additionally, the compound displayed significant beta-adrenoceptor intrinsic sympathomimetic activity. Evidence is presented that the beta-adrenoceptor antagonist and agonist properties of 5 are mediated via hydrogen-bond formation with the receptor.