TMED

TMED, (CH3)2NCH2CH2N(CH3)2. B.p. 122 C a hygroscopic base which forms a hydrocarbon-soluble stable chelate with lithium ions and promotes enhanced reactivity of compounds of lithium, e.g. LiAlH4, UC4H9, due to enhanced kinetic basicity of the chelate. Used in polymerization catalysts, tetramethyl lead, TML 5 lead tetramethyl. 

N,N, 1,1,2,2,8,8,9,9-Decamethyl-1,2,8,9-tetrasila[2.2](2,5)pyrrolo-phane (30) is prepared by a procedure similar to that applied to 28 and 29 through l,2-bis(A(-methylpyrrolyl)disilane 31 with slight modification of the reagents. The lithiation was performed with f-BuLi/ TMED. Under dilute conditions pyrrolophane 30 was obtained in 4% yield from 31 as air-stable colorless crystals besides a polymeric residue (35) (Scheme 7). 

The basic study was performed on copper complexes with N,N,N, N1-tetramethylethane-1,2-diamine (TMED), which were known to be very effective oxidative coupling catalysts (7,12). From our first kinetic studies it appeared that binuclear copper complexes are the active species as in some copper-containing enzymes. By applying the very strongly chelating TMED we were able to isolate crystals of the catalyst and to determine its structure by X-ray diffraction (13). Figure 1 shows this structure for the TMED complex of basic copper chloride Cu(0H)Cl prepared from CuCl by oxidation in moist pyridine. 

Figure 1. The structure of [TMED Cu(OH)tCu TMED]2 2Cl as determined by x-ray diffraction...

Figure 3. Effect of mineral base (NaOH) on the catalytic activity and specificity of the copper(II)-TMED complex. [CuCl2] = 3.33mM [DMP]0 = 0.06 M temp 25°C solvent 1,2-dichlorobenzene/methanol (9 1, v/v). The fraction DPQ was determined spectroscopically at 420 nm after 35% conversion.

The most useful approaches to the synthesis of di- and poly-ynes from terminal alkynes are undoubtedly the copper-catalyzed couplings discovered by Glaser (CuCl, NH4OH, EtOH, 02)," Eglinton [Cu(OAc)2, hot pyridine or quinoline, 02], and Hay [Cu(I), tmed, 02]. Some of the many applications of these reactions are discussed in the following. 

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