Group 13 amides aluminium

This result shows that is reasonable to neglect other type of interactions between aluminium ions and the polymer for instance coordination binding with amide groups,... 

The simple, salt elimination reaction of Equation (8.1) has been employed for amides of all the group 13 metals. In addition, it is currently the only well-established route to M(I) metal amides where M = Ga or Tl. The alkane elimination route of eqn. (8.2) is generally employed only for M = Al or Ga. This synthetic approach is also used for the metal imides (RMNR )n where a primary amine H2NR is the reactant. The use of metal hydrides, of which Equation (8.3) is but one example, is limited mainly to aluminium and, to a lesser extent, gallium because of the decreased stability of the heavier metal hydrides. 

Several other synthetic approaches, for example (i) transamination, (ii) the direct reaction between a primary or a secondary amine with a metal(III) halide, or (iii) the direct reaction of a metal (e.g. aluminium) and an amine in the presence or absence of hydrogen, as well as a number of other approaches (outlined in Chapter 4 of Ref. 1) have been known for many years and are occasionally employed. The procedure (iii), in particular, has been used for matrix isolation smdies of the simplest group 13 metal amides (see below). However, it is the three general approaches of Equations (8.1-8.3) that are by far the most commonly used. 

Stable aluminium amides with terminal —NH2 groups are rare. A simple example is [Al-(NH2)2( N(Dipp)C(Me) 2CH)], which was obtained by ammonolysis of the corresponding dichloride the Al—NH2 bond lengths are 1.789(4) A. The reaction of the Li N(H)Pr with... 

During studies on the total synthesis of Aspidosperma type alkaloids, unexpected difficulty was encountered in attempts to reduce the amide carbonyl group of the intermediate 1. Thus, many attempts to reduce 1 with lithium aluminium hydride resulted in reduction of both the amide carbonyl group and the C=C double bond. In an effort to circumvent this problem 1 was reacted with hot phosphorus oxychloride and the intermediate thus obtained treated with sodium borohydride in anhydrous methanol. The product which was isolated, however, was the pentacyclic compound 2, which was obtained in 50% yield. 

R)-Arbutamin was produced as follows 89.3 mg of (-)-l-di(t-butyldimethylsiloxy)phenyl)-2-aminoethanol, 50.0 mg of 4-(4-methoxymethoxyphenyl)butanoic acid, diethylphosphorylcyanide, and triethylamine were dissolved in N,N-dimethylformamide at 0°C, reacted at room temperature, so as to obtain 108.6 mg (in a yield of 82%) of amide compound. The amide compound obtained was reduced lithium aluminium hydride in an ether solvent at reflux temperature, so as to quantitative obtain amine. And 55.6 mg of (R)-arbutamin which is intended compound was obtained by deprotecting the hydroxyl-protecting group of amine in a methanol-THF solvent at room temperature using hydrochloric acid. 

Acylation of the C3 position can also be accomplished with acid chlorides, as illustrated in the synthesis of indole 7.34, a drug for the treatment of depression. Reaction of indole 7.31 with oxalyl chloride affords C3-substituted product 7.32 even though the benzene ring is very electron-rich. Conversion to amide 7.33 is followed by reduction with lithium aluminium hydride which removes both carbonyl groups, affording the target indole 7.34. 

EDCI), the nitrogen and hydroxy] groups were protected as the N,0-acetal 123.3 by reaction of 1232 with 2 2-dimethoxylpropane in acetone in the presence of trifluoroborane e the rate. Finally, reduction of the N me thoxy amide with lithium aluminium hydride afforded Garner s aldehyde in 88% overall yield for the 4-step sequence. Epimerisation of the stereogenic centre is negligible under these conditions. 

Lithium aluminium hydride is highly reactive and can also reduce carboxylic acids, acid chlorides, anhydrides, esters, lactones, amides, lactams, imines, nitriles and nitro group. For example, -COCI, -CO2H, -C02Et, -CHO and >CO are reduced to -CH2OH or >CHOH, provided the correct solvent is used. 

The trihalogenomethyltin compounds can be prepared by acidolysis of a tin amide R3SnNEt2 (R = Me, Bu, or Ph) with the haloform HCX3 (X = Cl, Br, or I), and the CX3 group can then be reduced to CHX2 and CH2X with lithium aluminium hydride.14... 

The best results before organic catalysis were with amides 125 and Lewis acid catalysts based on Al, Ti, and Cu(II) with C2-symmetric ligands. Corey s aluminium complex 127 derived from the diamine whose resolution was described in chapter 22 works well with substituted cyclo-pentadienes 124 and the product 126 was used in prostaglandin synthesis.28 There are three aspects of stereoselectivity in this reaction which diastereotopic face of 124 is attacked (that anti to the CH2OBn group), is the product exo or endo (endo) and which endo product is formed, 126 or its enantiomer Only for the last question is asymmetric catalysis necessary, though Lewis acid catalysis of any kind enhances endo/exo selectivity. 

We reasoned that the /-butyl group is still too small for an efficient chiral induction therefore, the optically pure 0-TBDPS lactaldehyde was chosen for the formation of the N,O-acetal. But only amides 39 and 41 are now non-racemic 39 exhibits a satisfactory chiral induction on allylation, because the enolate carbon is shielded by the adjacent axial bulky substituent. In 41, both sidechains at C-2 and C-4 are equatorial and the stereocontrol drops significantly.The use of a chiral aldehyde for acetal formation even allows the use of the achiral O-aminobenzylalcohol (43) as a template. Acetals 44 and 45 are formed and separated due to the allylic 1,3-strain of the amide moiety both derivatives have axial sidechains (as detectable in the crystal structure of alkylation product 46d) (Fig. 2) and the chiral induction is similarly high in both cases. The chiral auxiliary is removed with lithium aluminium hydride without any racemization of the newly created stereocenter (6). 

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