CHIRAL POLYMETHINE DYES - PART 6 - SYNTHESIS, ABSOLUTE-CONFIGURATION,UV VIS SPECTROSCOPIC, AND CHIROPTICAL PROPERTIES OF CHIRAL TRIMETHINIUM AND PENTAMETHINIUM CYANINE DYES WITH 1,2,3,4-TETRAHYDRO-3,6-DIMETHYLQUINOLYL END-GROUPS/

Starting with monochiral 1,2,3,4-tetrahydro-3,6-dimethyl quinoline 14a ,b (Schemes 1 and 2), we have synthesized the new chiral, symmetrical and unsymmetrical, tri- and pentamethinium streptocyanine dyes 2a (Sch eme 8), 4a (Scheme 5), and 5a,b (Scheme 4), resp. 9a (Scheme 6), 10a,b (Scheme 4), and 11a (Scheme 7) with one or two stereogenic centers in the two heterocyclic end groups. The absolute configuration of 14a,b, and thus the absolute configuration of all monochiral polymethinium d yes derived from 14a,b has been determined by a single-crystal X-ray a nalysis of its 4-bromobenzenesulfonyl derivative 17a (Scheme I and Fig . 1). The UV/Vis spectroscopic and chiroptical properties of the new p olymethinium dyes have been studied for the first time and compared wi th that of similar streptocyanine dyes synthesized earlier (Tables 1 a nd 2) in order to find possible correlations between chiroptical prope rties and molecular structure.