- Easier preparation of 2,6-Di-tert-butylphenyl derivatives 1
-
Despite steric shielding by the 2,6-di-tert-butylphenyl group (super-2,6-xylyl=xyl*), inexpensive sodium phenolate (xyl*-ONa) reacts with dimethyl sulfate to produce only xyl*-OCH3 (94%) with complete suppression of the alternative 4-methylation. Reductive cleavage of xyl*-OCH3 by elemental lithium with the help of an electron carrier generates xyl*-Li, which in turn yields xyl*-CO2H (63%). The corresponding 4-methyl-derivatives of these compounds were obtained analogously. The acid chloride xyl*-COCl (77% yield) acylates HalMgCH 2R to give only xyl*-COCH3 (86%) or xyl*-COEt (97%). These two ketones react with n-butyllithium (no carbonyl addition) and Cl-PO(OEt)2 to furnish only the enol phosphates xyl*-C(=CH 2)OPO(OEt)2 (84%) or xyl*-C(=CHCH 3)OPO(OEt)2 (up to 70%), respectively. Only 1,2-elimination occurs when the latter two products are treated with tert-butyllithium, affording xyl*-CCH (68%) or xyl*-CCMe (88%), respectively. Georg Thieme Verlag Stuttgart - New York.
- Knorr, Rudolf,Rossmann, Eva Christine,Knittl, Monika
-
scheme or table
p. 2124 - 2128
(2010/09/04)
-
- Der Einbau von Magnesium in Liganden der Chlorophyll-Reihe mit (2,6-Di-t-butyl-4-methylphenoxy)magnesiumjodid
-
Experimental details are given for the new method of introducing magnesium into porhpinoid ligands by (2,6-di-t-butyl-4-methylphenoxy)magnesium iodide (1), previously published in preliminary form .Besides magnesium octaethylporphyrinate (14), methyl pyrochlorophyllide a (10), methyl chlorophyllide a (8), and methyl bacteriochlorophyllide a (12), the complexation of pheophytin a (2) to chlorophyll a (3) and of pheophytin b (4) to chlorophyll b (5) are described.
- Zass, Engelbert,Isenring, Hans Peter,Etter, Rolf,Eschenmoser, Albert
-
p. 1048 - 1067
(2007/10/02)
-