Study on the Lithiation Reaction of 3-Diisopropylcarbamoyl-N-pivaloylphenylethylamine

As a continuation of our earlier studies on the lithiation-based synthesis of 8-methoxy-, 8-fluoro- and 8-chloro-3,4-dihydroisoquinoline, a similar approach was investigated for the preparation of the 8-diisopropylcarbamoyl congener. The corresponding N-pivaloyl phenylethylamine key intermediate was prepared via four new bifunctional intermediates in high overall yield. Lithiation of this intermediate followed by quenching with dimethylformamide led to a mixture: beside the desired compound containing the formyl moiety in the common ortho position of the two aromatic substituents, the isomer formylated in the other ortho position of the carbamoyl moiety was surprisingly obtained as the major product. The crude mixture could finally be transformed under acidic conditions to the target compound, 8-diisopropylcarbamoyl-substituted 3,4-dihydroisoquinoline, albeit in a low yield

Assignment of Absolute Configuration to Enantiomers of Anti-Alzheimer Drug Candidate Blarcamesine

Blarcamesine is a promising investigational drug for the treatment of Alzheimer's disease. The international nonproprietary name blarcamesine refers to a racemic compound, although it seems likely that it will be marketed in an enantiopure form. A resolution process has been described in the literature, but the absolute configurations of the enantiomers have not yet been disclosed. In the present study, crystals of (R)-(-)- and (S)-(+)-mandelate salts of (+)- and (-)-blarcamesine and also that of (R)-(+)-blarcamesine itself, suitable for single-crystal X-ray diffraction measurement were prepared and the absolute configurations of (+)- and (-)-blarcamesine have been determined

Synthesis of 1,2-dihydroisoquinoline-3-carbaldehydes. [Erratum to document cited in CA117(15):150854e]

An error in the omission of an author has been cor. Omitted Acknowledgments have also been provided. Only the author error was reflected in the abstr. (the heading) and the index entries. [on SciFinder (R)

o-Selective metalation and electrophilic substitution of benzylamine derivatives

N-Pivaloylbenzylamines and derivs. [e.g., 2,4-R(MeO)C6H4CH2NHCOCMe3, I, R = H] undergo smooth ortho-metalation when treated with two equivs. of an organolithium reagent. Subsequent carboxylation or hydroxylation lead to a no. of products, e.g., I, R = CO2H, OH. [on SciFinder (R)

An easy and versatile access to 8-substituted isoquinolines

Lithiation of N-(2,2-diethoxyethyl)benzylamines I (R = Me, PhCH2) and reaction with electrophiles followed by acid-catalyzed cyclization leads to isoquinolines II (R1 = Me, MeO, CH2OH, MeS, Cl, Br, iodo) in 37-75% yield. [on SciFinder (R)

3-Amino-2-arylpropanoic acids by electrophilic substitution of 2-arylethylamines at the benzylic position

Title amino acids I (R, R1, R2 = H, OMe) were prepd. from 2-arylethylamines II by a reaction sequence consisting of N-pivaloylation, lithiation at the benzylic position with tert-BuLi, carboxylation, and deprotection by refluxing in 20% hydrochloric acid. [on SciFinder (R)

8-Methoxyisoquinoline derivatives through ortho-selective metalation of 2-(3-methoxyphenyl)ethylamine

Butyllithium in Et2O smoothly metalates 3-MeOC6H4CH2CH2NHCOCMe3 at the ortho position flanked by the two substituents. Subsequent reaction with DMF followed by acid catalyzed cyclization and redn. gives 8-methoxy-1,2,3,4-tetrahydroisoquinoline (I). [on SciFinder (R)