Zur Herstellung von I-Alkyl-oder l-Aryl-3,4-dihydroisochinolinen 1 dient haufig die Bischler-Napieralski-Reaktion, deren praparative Breite mit zahlreichen Beispielen belegt ist Ublicherweise erhitzt man dabci ein N-Acylphenethylamin rnit POCl,, PCls oder P401" in einem relativ hochsiedenden Losungsmittel. Aus N -(a-MonohalogenacyI)phenethylaminen erhalt man in guten bis inaligen Ausbeuten auch die entsprechenden Heterocyclen 1 (R3 = CH'CI 3-6i, CH2Br4j, CHCICH, 'I). Dihydroisochinoline rnit hoher halogenierten Alkylresten in Position 1 lassen sich dagegen rnit P0Cl3 offenbar nicht gewinnenx-l"i.
Synthesis of Galactose-Cluster-Containing Steroid DerivativesThe synthesis of galactose Clusters that are linked to a Steroid moiety by a peptide-like spacer unit is described. The galactose Cluster is obtained by Koenigs-Knorr glycosylation of TRIS-Gly-Fmoc (2 b) under Helferich conditions. Peptide and ester bonds are formed after activation of carboxylic acids as diphenylthiophene dioxide (TDO) esters. 6a is synthesized in a convergent way by coupling of (Ac 4 Gal) 3 -TRIS-Gly (3e) with cholesteryl TDO succinate (5b). Coupling of (Ac 4 Gal) 3 -TRISGly hydrogen succinate (3f) with Gly-O-Chol (5d) by means of EEDQ yields 6d. Reaction of (Ac 4 Gal) 3 -TRIS-Gly-SUCC-0-TDO (3 g) with 25-hydroxycholesterol leads in a linear sequence to the oxysterol derivative 6f. Selective cleavage of the acetyl groups from galactose units yields the known Compound 6 b and the new derivatives 6e and 6g.
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