Amines homochiral

The Zr-catalyzed asymmetric alkylation shown in Eq. (2) [8] illustrates two important principles (1) The catalytic asymmetric protocol can be readily applied to the synthesis of non-aryl imines to generate homochiral amines that cannot be prepared by any of the alternative imine or enamine hydrogenation protocols. (2) The catalytic amine synthesis involves a three-component process that includes the in situ formation of the imine substrate, followed by its asymmetric alkylation. This strategy can also be readily applied to the preparation of arylamines. The three-component enantioselective amine synthesis suggests that such a procedure maybe used to synthesize libraries of homochiral amines in a highly efficient and convenient fashion. 

The results from the reaction of ( )-2-butene and 3-phenoxy-l-propene using (5)-1-phenyl-ethanamine as the homochiral amine are shown in Table 4. Low yield and/or low asymmetric induction were generally observed. Lack of regioselectivity was observed with 1-butene. 

It has recently been shown that aminotransferases can be used to produce homochiral amine products that do not contain an a-carboxylic add (17,18,48). Enzymes capable of catalyzing such reactions belong to the group of (o-aminotransferases. The reversible nature of the transamination reaction makes it possible for both enantiomers of a given amine to be produced using a single enzyme (Fig. 18). The racemic amine can be... 

Attempts to induce asynunetry at an imine carbon using homochiral amines to form Schiff bases followed by 1,2-additions with organocopper reagents has not produced a viable method as yet. Yamamoto... 

Chiral phosphoramides, particularly C2-symmetric examples, are widely used in asymmetric synthesis (see section 3.2). One example is the asymmetric catalysis of Aldol reactions, where the phosphoramide catalyst is used in combination with a Lewis base. A solid state and solution study of the structure of chiral phosphoramide-tin complexes used in such reactions has now been reported. A number of chiral, non-racemic cyclic phosphoramide receptors (387) have been synthesised and their interactions with homochiral amines studied using electrospray ionisation MS. Although (387) bind the amines strongly, no evidence of chiral selectivity was found. Evidence from a combination of its X-ray structure, NMR, and ab initio calculations suggests that the cyclen phosphorus oxide (388) has an N-P transannular interaction in the solid state. A series of isomers of l,3,2-oxazaphosphorino[4,3-a]isoquinolines(389), containing a novel ring-system, have been prepared and their stereochemistry and conformation studied by H, C, and P NMR spectroscopy and X-ray crystallography... 

The cycloaddition is ascribable to the oxyanion of hydrogen-bonded enolate (ArO —HNEt3 ) rather than to the hydrogen-bonded enol (ArOH—NEtj). An enantioselective version of the reaction was achieved by using a homochiral amine [27]. Similarly the reactions with less reactive dienophiles such as dimethyl fumarate, fumaronitrile, maleonitrile and methyl acrylate give the Diels-Alder adducts quantitatively when the cycloadditions are carried out in THF or CHCI3 in the presence of EtjN, while in MeOH Michael adducts were isolated. Experimental evidence supports the hypothesis that the base-catalyzed cycloadditions of anthrone with dienophiles are concerted Diels-Alder processes [25b]. 

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