New macrocyclic ligands: XV.* isomeric, benzylated and xylyl-linked macrocyclic ligands derived from selectively protected N3O2-donor rings
Park, Kyoung Ju, Kim, Jin-Ho, Nishimura, Tomoko, Meehan, George V., Lindoy, Leonard F., Lee, Shim Sung, Park, Ki-Min, and Yoon, Il (2002) New macrocyclic ligands: XV.* isomeric, benzylated and xylyl-linked macrocyclic ligands derived from selectively protected N3O2-donor rings. Australian Journal of Chemistry, 55 (12). pp. 773-778.
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View at Publisher Website: http://dx.doi.org/10.1071/CH02164
Direct alkylation of the N3O2-macrocycle 1,12,15-triaza-3,4 : 9,10-dibenzo-5,8-dioxacycloheptadecane (1) with benzyl bromide in the presence of sodium hydrogen carbonate (in the respective molar ratios 1.0 : 2.0 : 1.3) led to a mixture of the mono-, bis-, and tris-N-benzylated derivatives (2)–(6) which were separated using their differential solubilities in warm acetone, fractional crystallization, coupled with column chromatography on silica gel. The X-ray structure of the symmetrical dibenzylated product (4) (as its HNO3 salt) is described. In a parallel study, N-protection of (1) using 1.7 molar equivalents of di-tert-butyl dicarbonate (Boc)2O yielded a mixture from which the symmetrical and unsymmetrical di-protected isomers (8) and (9) were separated by chromatography. Reaction of the symmetrically protected derivative (8) with benzyl chloride in the presence of excess sodium carbonate, followed by removal of the Boc groups, provided an alternative route to the corresponding (symmetrical) mono-N-benzylated macrocycle (2). A similar strategy, involving the use of α,α′-dibromo-p-xylene as a dialkylating agent, was employed to bridge a pair of N-diprotected macrocycles of type (8) or (9) to yield isomeric linked products (12) and (14), respectively. Deprotection of the resulting bis-macrocyclic products gave the 'central' and 'side' linked ligands (13) and (15), respectively.
|Item Type:||Article (Refereed Research - C1)|
|FoR Codes:||03 CHEMICAL SCIENCES > 0305 Organic Chemistry > 030503 Organic Chemical Synthesis @ 51%|
03 CHEMICAL SCIENCES > 0303 Macromolecular and Materials Chemistry > 030302 Nanochemistry and Supramolecular Chemistry @ 49%
|SEO Codes:||97 EXPANDING KNOWLEDGE > 970103 Expanding Knowledge in the Chemical Sciences @ 100%|
|Deposited On:||08 Jul 2009 09:25|
|Last Modified:||18 Oct 2013 00:23|
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