- Difunctional derivatives of bis(m-phenylene)- 32-crown-10
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Optimization studies of the condensation of methyl 3,5-dihydroxybenzoate (1) with tetra(ethylene glycol) dichloride (3) resulted in improvement of the yield of the 1 + 1 cyclization product, 5-carbomethoxy-m-phenylene-16-crown-5 (5), to 67% (HPLC), but no improvement in the yield (28%, HPLC) of the desired 2+2 product, bis(5-carbomethoxy-m-phenylene)-32-crown-10 (4). However, after optimization, a two-step procedure provided improved yields of 4 and this procedure was generalized to afford other difunctional monomers. Condensation of substituted resorcinols with 3 and subsequent transformations yielded substituted (R) 3,5-bis(11-chloro-3,6,9-trioxaundecyl-oxy)benzenes (7, 9-14). Reaction of dihalides 7 (R = COOCH3), 13 (R = CHO), and 12 (R = CH2OSi(Me)2-t-Bu) with methyl 3,5-dihydroxybenzoate (1) produced bis(5-carbomethoxy-m-phenylene)-32-crown-10 (4) (43%), 5-carbomethoxy-m-phenylene-5′-formyl-m′-phenylene-32-crown-10 (15) (32%), and the lactone (16a) (18%, derived from the initially formed 5-hydroxymethyl-m-phenylene-5′-carbomethoxy-m′-phenylene-32-crown-10 (16)), respectively. Subsequent reactions gave the corresponding diacid (17), bis(hydroxymethyl) (19), bis(bromomethyl) (20), diacetyl (18), diformyl (21), bis(p-nitrophenoxymethyl) (22), and di(acetoxymethyl) (23) derivatives.
- Gibson, Harry W.,Nagvekar, Devdatt S.
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p. 1375 - 1384
(2007/10/03)
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- Metal-assisted Reactions. Part 17. Ring-opening and Dimerization of Cyclic Ethers by Titanium Halides
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Reaction of TiCl4 or TiBr4 with a variety of cyclic ethers gives, predominantly, products resulting from simple ring-opening or from ring-opening with simultaneous condensation to dimeric species.The variations in yields of these two kinds of products might be correlated qualitatively with an initial formation of the complex TiX4*2E (X = Cl or Br; E = cyclic ether) in which the ethers were held in a cis or trans relationship.Although such a correlation might suggest that TiCl4 but not TiBr4 exerts a template effect on the condensation, stereochemical considerations of the reaction products indicate otherwise.TiCl3 and VCl3 do not give similar results and TiF4 gives no reaction.
- Delaney, Paul A.,Johnstone, Robert A. W.,Entwistle, Ian D.
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p. 1855 - 1860
(2007/10/02)
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