Coupling 1 - ethylamine

Potassium borohydride reduction of runanine (17) yielded dihydro-runanine (24), the H-NMR spectrum of which (Table II) exhibited a triplet (64.25), the proton bearing the hydroxyl group coupling with those of C-5 (35). The optical activity of runanine (17), [a]D —400°, was similar to that of hasubanonine (5), [a]D —214° (3) therefore, it was concluded that the ethylamine linkage must have the same configuration as hasubanonine [C-13 (R) and C-14 (S)]. From these results, structure 17 was proposed for runanine (35) however, no application of mass spectral data to the structure elucidation was presented (35). 

More recently, Somfai and coworkers have reported on the efficient coupling of a set of carboxylic acids suitable as potential scaffolds for peptide synthesis to a polymer-bound hydrazide linker [24]. Indole-like scaffolds were selected for this small library synthesis as these structures are found in numerous natural products showing interesting activities. The best results were obtained using 2-(7-aza-l H-benzo-triazol-l-yl)-l,l,3,3-tetramethyluronium hexafluoride (HATU) and N,N-diisopropyl-ethylamine (DIEA) in N,N-dimethylformamide as a solvent. Heating the reaction mixtures at 180 °C for 10 min furnished the desired products in high yields (Scheme 7.4). In this application, no Fmoc protection of the indole nitrogen is required. 

A diastereoselective imine alkylation and a palladium-catalysed biaryl coupling were important steps in the diastereoselective synthesis of 6,7-dihydro-5//-dibenz[c,e]azepines (Scheme 7) starting from (R)-l-(2-methoxyphenyl)ethylamine. Selection for the... 

Intermediate diketopiperazine derivatives have been employed in the diastereoselective synthesis of benzyltetra-hydroisoquinoline by 1,4-chirality transfer. iV-Cbz-Proline was coupled with 2-(3,4-dimethoxyphenyl)ethylamine and the resulting amide 109, after deprotection, was reacted with phenylpyruvic acid (Cbz = carbobenzyloxy group). Compound 110 underwent acid-catalyzed Pictet-Spengler condensation to yield final tetracyclic... 

In another method for the coupling of two different allylic groups,1346 a carbanion derived from a p.-y-unsaturated thioether couples with an allylic halide.1347 The product contains an SPh group that must be removed (with Li in ethylamine) to give the 1,5-diene, but this... 

Fig. 8. Classification of ESR spectra (—296 K) of solutions of alkali metals in a variety of nonaqueous solvents rM is the electron-cation encounter lifetime, and A is the metal hyperfine coupling constant, in hertz THF = tetrahydrofuran, EA = ethylamine, DG = diglyme, MA = methylamine (—220 K), 1,2PDA = 1,2-propanediamine, EDA = ethylenediamine, AM = ammonia (—240 K).

Compounds with a terminal acetylenic function, RCsCH, react with 1-bromoalkynes, R CsCBr in the presence of an aliphatic amine and a catalytic amount of a copper salt to give the coupling products RCsCCsCR. This useful reaction, discovered by Cadiot and Chodkiewicz [195], gives a ready access to a number of poly-unsaturated systems. The usual procedure involves dropwise addition of the bromoacetylene R GsCBr to a mixture of the acetylene RCsCH, ethylamine, ethanol or methanol, a catalytic amount of copper chloride or bromide and a small amount of hydroxylamine.HCl. This reducing agent prevents the oxidation to copper ). The reaction is usually very fast at temperatures in the region of 30 C. Since much heat is evolved, the reaction can be monitored easily by temperature observation. 

Add 15 pX of coupling reagent (ethanobtri-ethylamine PITC water [7 1 1 1]), mix, and incubate at room temperature for 20 min. 

Kirmse and coworkers have studied the reaction of alkanediazonium ions with amines and with lithium azide Cyclopropanediazonium ions give azo coupling products 6 and 7 with dimethylamine and with ethylamine, respectively (1) K However, no azo coupling of 1 with phenols was observed. In the reaction... 

In addition to the head-to-head cross-coupling reactions, it has been discovered that the reaction of phenyl or 1-alkenyl iodides with (E)-l-alkenyl-l,3,2-benzo-dioxaboroles produces the head-to-tail cross-coupling products, 2-phenyl-1-alkenes or 2-alkyl-1,3-alkadienes, respectively (Eq. 107) The reaction is profoundly affected by catalytic quantities of palladium compounds (Pd black prepared by reduction of Pd(OAc)j with diborane is especially effective) in the presence of tri-ethylamine. 

The reaction is carried out by slowly adding the 1-bromoalkyne to a solution containing the terminal alkyne, amine, copper(i) chloride and hydroxylamine hydrochloride. The amine, usually ethylamine, is used in excess, e.g. 1-8 moles/mole of alkyne, and catalytic quantities (1-5 mol %) of copper(i) chloride are used. One of the side-reactions is the self-coupling of the bromoalkyne induced by Cu(i) which in turn is oxidized to Cu(ii) (equation 11). The hydroxylamine salt serves to reduce the copper back to the cuprous state. 

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