Preparation of diaryl ethers from tyrosine or 4-hydroxyphenylglycine using organomanganese chemistry

Abstract

Diaryl and polyaryl ethers are important subunits in a wide variety of natural products,1 but the commonly used method for constructing the ether linkage, i.e., Ullman coupling,2 proceeds only under quite harsh conditions. One Combustion analyses were determined by Galbraith, Inc.,

Diaryl Ether Formation in the Synthesis of Natural Products

“…[15] Pearson's work dominates the field of the synthesis of naturally occurring diaryl ethers by this method (Scheme 2, R 1 = η 6 -Ru + CpPF 6 -). [105,107] Several diaryl ethers related to vancomycin (35), [106] orienticin C (36), [113] teicoplanin (37), [110] and complestatin (39) [115] were thus accessible by this method without any epimerization of sensitive amino acids during the coupling or photochemical diaryl ether liberation steps. [105,107] Several diaryl ethers related to vancomycin (35), [106] orienticin C (36), [113] teicoplanin (37), [110] and complestatin (39) [115] were thus accessible by this method without any epimerization of sensitive amino acids during the coupling or photochemical diaryl ether liberation steps.…”

“…[105][106][107][108][109][110][111][112][113][114] Initial model studies helped to establish that ruthenium is better suited than manganese or iron for such applications because: i) it can be attached to the aromatic moiety without affecting bystander functional groups, ii) the resulting Ruarene complexes are stable to various chemical transformations and yet highly activated to participation in S N Ar reactions with preformed phenoxides at low or ambient temperature, and iii) the diaryl ether can be easily liberated from the immediate product (also a Ru-arene complex) by mild photochemical methods. [105,107] Several diaryl ethers related to vancomycin (35), [106] orienticin C (36), [113] teicoplanin (37), [110] and complestatin (39) [115] were thus accessible by this method without any epimerization of sensitive amino acids during the coupling or photochemical diaryl ether liberation steps. The disadvantages of the method are: i) the need for the use of stoichiometric ruthenium complexes (although they can be recovered, usually in Ͼ80 % yields), ii) the difficulty in purifying cationic ruthenium complexes, [116] and iii) no example of halogenated diaryl ether construction exists.…”

A Novel Approach to the Synthesis of Some 2-Aryl Alkanoic Acid Esters

“…Although some of these alkanoic acid esters have been prepared previously'-3, our method offers an alternative route to the synthesis of these compounds with high efficiency, high yield, accessibility and low cost of the starting materials. 10 ml DMF was stirred under nitrogen with heating f o r 8h at 5OoC. The red reaction mixture was filtered rapidly into 15 ml of 10% hydrochloric acid, the reaction flask washed with ethanol and the washing also filtered into the HC1.…”

Synthesis of a deoxyristomycinic acid derivative using organomanganese chemistry

“…5 ~ solution in hexanes). After 20 min the solid arene-manganese complex (6) (1.256 g, 2.0 mmol) was added and the mixture was stirred at -78 "C for 30 min, quenched rapidly with aq. ammonium chloride at -78 "C, and extracted with diethyl ether in the usual way.…”

“…Hz), 6.96 (1 H, t, J2.0 Hz), 6.77 (1 H, ddd, J8.0,2.1,0.9 Hz), 6.71 (1 H, d, J 1.0 Hz), 6 dropwise 0.25~-hydrochloric acid (20 ml). The reaction mixture was stirred overnight at room temperature, extracted with diethyl ether (3 x 10 ml), and the remaining aqueous solution was adjusted to pH 8 by the addition of conc.…”