7-Hydroxy isoquinoline

Isocytosine, 374 Isodialuric acid, 377 Isonieotinic acid, 333 Isoquinoline hydroxy-, 352, 355, 384 1-hydro xy-2- 2,4-dinitrophenyl) -1,2-dihydro, 179... 

The Pictet-Gams method involves the cyclization of P-hydroxy- or P-methoxy- P-phenethylamides, and produces the isoquinoline derivative rather than the reduced form. A further extension of method is based on a metboxyetbyl amine. 

Ha.loisoquinolines, The Sandmeyer reaction is commonly used to prepare chloroisoquinolines from the amino compound. The corresponding hydroxy compounds are also used by treatment with chlorides of phosphoms. The addition of bromine to a slurry of isoquinoline hydrochloride in nitrobenzene gives a 70—80% yield of 4-bromoisoquinoline [1532-97-4J. Heating 1-chloroisoquinoline [19493-44-8] with sodium iodide andhydriodic acid gives 1-iodoisoquinoline [19658-77-6] (179). 

Isoquinoline, l-chloro-3-hydroxy-tautomerism, 2, 152 Isoquinoline, 3-cyano-synthesis... 

Isoquinoline, l-(dimethylamino)-methylation, 2, 179 Isoquinoline, halo-lithium derivatives, 2, 363 Isoquinoline, 3-halo-nucleophilic substitution, 2, 59 Isoquinoline, l-halo-3-hydroxy-synthesis... 

Diels-Alder cycloaddition reactions, 2, 350 tautomerism, 2, 27, 152, 347 Isoquinoline, 4-hydroxy-alkylation, 2, 349 sulfonation, 2, 321... 

One important variation of the Bischler-Napieralski reaction is the Pictet-Gams modification, in which p-hydroxy or -alkoxy phenethylamides 38 are converted to isoquinolines 39. This transformation is covered in detail in section 9.12 of this text. 

The isoquinoline framwork is derived from the corresponding acyl derivatives of P-hydroxy-P phenylethylamines. Upon exposure to a dehydrating agent such as phosphorous pentaoxide, or phosphorous oxychloride, under reflux conditions and in an inert solvent such as decalin, isoquinoline frameworks are formed. 

The a and y are used to denote the position of a substituent relative to a cyclic hetero atom thus 4-hydroxy isoquinoline is a /3-hydroxy compound. 

Dehydrodiscretamine (72), Thalifedine (73), Thalidastine (74), Fissisaine (75), Stepharanine (76), and Dehydrocorydahnine (77) are additional examples of alkaloids, which possess the 7-hydroxy-isoquinoline moiety which on deprotonation yields conjugated mesomeric betaines (Scheme 27). In either case, the rr-electron system is extended by substitution... 

As shown in Scheme 26, Papaverine hydrochloride yields a separable mixture of Protopapaverine (67) and the salt norpapaverinium chloride (68) when heated slightly beyond its melting point for several minutes. Molecule 67 can exist as conjugated mesomeric betaine 67A (7-hydroxy form) or as 2-substituted-2//-isoquinolin-6-one 67B (6-hydroxy form) (66TL1177). Similar structures were described as zwitterionic pentacyclic... 

Fluorophenyl)-l ]-hydroxy-2,3,4,1 ]-tetrahydro-6/7-pyrimido[],2-Z)]-isoquinolin-6-one was obtained in the reaction of l-(4-fluorophenyl)-3-oxo-],3-dihydro-2-benzofuran-l-carboxamide and 1,3-diaminopropane in boiling toluene (01BMCL339). 

Alkoxy-3-(4-biphenyl)perhydropyrido[], 2-c][], 4]oxazines were obtained from 3-hydroxy derivative with PrOH and Br(CH2)30H in a boiling acidified medium (00JMC609, 00MIP13). Spontaneous dehydration of b-hydroxy-1,3,4,6,7,1 lZ -hexahydro[l,4]oxazino[3,4-n]isoquinolin-4-one 258 in CHCI3 gave 3,4,6,7-tetrahydro derivative 259 (97JOC2080). 

Nitration of 2-cyclohexyl-8-hydroxy-2,3,4,6,11,11 u-hexahydro-1 //-pyra-zino[l,2-6]isoquinoline-l,4-dione with 70% HNO3 at room temperature for 30 min afforded an 1 1 mixture of 7- and 9-nitro derivatives (98MIP7). 

Hydroxy group of 8-hyd oxy-2-cycloalkyl-2,3,4,6,ll,lla-hexahydro-l//-pyrazino[l,2-i]isoquinoline-l,4-diones was alkylated with allyl bromide, 2-(bromodifluoromethyl)pyridines, l-(bromodifluoromethyl)- and l-(bro-momethyl)benzenes, halomethyl derivatives of different heterocycles (pyridine, pyrazine, pyrazole, pyrrole, thiazole, thiophene) in the presence of CS2CO3 or K2CO3 (98MIP7). Hydroxy group of 8-hydroxy-2-cyclopentyl-... 

Cyclocondensation of 2-(2-chloroacetyl)-l, 2,3,4-tetrahydroisoquinoline-3-carboxylate 418 (R =N02, R = Me) with liquid NH3 in MeOH in a stainless steel pressure vessel at room temperature overnight gave 8-nitro-2,3,4,6,1 1,1 la-hexahydro-l//-pyrazino[l,2-i]isoquinoline-l,4-dione (419, R=H, R =N02) (97MIP4). (1 la/i)-2-Cycloalkyl-8-hydroxy-2,3,4,6,ll, 1 la-hexahydro-l//-pyrazino[l,2-i]isoquinoline-l,4-diones 419 (R = cycloalkyl, R = OH) were prepared in the reactions of (3/i)-2-chloroace-tyl-l,2,3,4-tetrahydroisoquinoline-3-carboxylate (418, R = OH, R = Et) with cycloalkylamines (98MIP7). 

Inhibition of human multidrug resistance P-glycoprotein 1 was investigated by analogs of a potent. 5-opioid antagonist, including (35, 1 lu5)-3-[(4-hydroxy-2,6-dimethylphenyl)methyl]-11,11 u-dihydro-2//-pyrazino[l, 1-b] isoquinoline-l,4(3//,6//)-dione (OIMIIO). Opioid antagonist activity of... 

The thermal condensetion of p-benzyloxyphenylacetic acid and of 3-methoxy-4-hydroxy-phenethylamine occurs and gives, with a yield of 86% to 92%, the N-(3-methoxy4-hydroxy-phenethyl-p-benzyloxyphenylacetamide from this latter, by cyclization according to Bischler-Napieralski with phosphorus oxychloride in acetonitrile, followed by reduction with sodium borohydride, there is obtained with a yield of 75% to 80% the 1-(p-benzyloxybenzyl)-6-meth-oxy-7-hydroxy-1,2,3,4-tetrahydroisoquinoline, which is methylated with formaldehyde and formic acid giving 1 (p-benzyloxybenzyl)-2-methyl-6-methoxy-7-hydroxy-1,2,3,4-tetrahydro-isoquinoline with a yieid of 90%. 

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