Amino allylation

Another domino process, designed by Polt and coworkers [16], deals with the consecutive transformation of an in situ-prepared aldehyde to give 3-amino allylic alcohols 7-31 from 3-amino acids. When the 3-amino acid ester derivative 7-29 is sequentially treated with iBu5Al2H and vinyl magnesium bromide, a 3 2 mixture of the allylic alcohol derivatives 7-30 is obtained in 60% yield, which can be hydrolyzed to give 7-31 (Scheme 7.10). 

Add 1 /A of sodium bicarbonate 1 M (pH 9.0) to the amino-allyl labeled cDNA solution. 

Incubate at room temperature for 1 h to allow coupling of the dye to the amino-allyl groups. 

Steiically congested cw-aziridines such as 137 were prepared from the deiivatized amino allyl alcohol precursor 136 through a palladium-catalyzed cyclization reaction <99TL1331>. This methodology has also been extended to the cyclization of amino allenes <99JOC2992>. 

The synthesis of a -amino allylic alcohols is particularly difficult, yet this functionality is important in natural products (such as sphingosine) or as a synthon for further elaboration to amino sugars. In synthetic studies of this moiety204, the corresponding enones, with adjacent stereocenters, have been efficiently reduced to the allylic alcohol in quantitative yields and in both a regiocontrolled (1,2) and a stereocontrolled fashion (equation 53). The syn anti ratio of the product depends upon the hydride reductant and solvent being utilized. A 4 1 ratio was obtained with L-selectride and a 1 6 ratio obtained by the use of DIBAL in toluene. 

Y. Liu, G. Asymmetric synthesis of a-amino allyl, benzyl, and propargyl silanes by metalation and rearrangement. Org. Lett. 2003, 5, 1859-1861. 

Allylic amination." In the presence of l d(O) catalysts, primary and secondary amines react with (E)- or (Z)-y-acetoxy or y-chloro allylic alcohols or acetates to form (E)-y-amino allylic alcohols or acetates. 

A large number of different a,(o-bis[(trifluoromethyl)sulfonyloxy]-substituted organosilicon compounds can be obtained by relatively simple methods from the corresponding amino-, allyl-, or phenylsilanes. Moreover, it is remarkable that these silyl triflate derivatives are often easily formed, when the synthesis of the corresponding chloro- or bromosilanes is difficult or does not appear to have been attempted. Eq. 2 and Eq. 3 show selected examples of this synthesis [10-12]. The products were prepared in high purities and yields. The resulting triflates should be used for the polycondensation without further purification, because they often cannot be destilled without decomposition. 

Low 1,2-diastereoselection is also found in the thermal rearrangement of trichloroacetimidates derived from chiral <5-amino allylic alcohols54 55, which is contrary to the results of the palladium-catalyzed rearrangement (see Section 7.6.1.2.). 

The three component aminoallylation reaction of the activated olefins 4 was also reported by us (Scheme 7) [39]. The palladium catalyzed reaction between phthalimid 10, olefins 4 and allyl chloride 11 proceeded well in the presence of CS2CO3 to give the corresponding amino allylation products 12 in high yields. Likewise, cyanoallylation of activated olefins was also reported (Scheme 8) [40]. In both cases only aryl substituded and t-butyl substituded olefins are proved good substrates. The mechanism of these reactions is presumably similar to that of hydroalkoxylation reaction (see Scheme 5). 

The enantioselective total synthesis of (-)-cassine was accomplished in the laboratory of H. Makabe." The synthetic sequence involved a key, highly diastereoselective PdCi2-cataiyzed cyciization of an amino allylic alcohol. The cyclic product was then subjected to hydroboration with 9-BBN followed by oxidation to afford the desired primary alcohol, which was converted to (-)-cassine. 

In sharp contrast to the coupling of the l,2-bis(diisopropylamino)-3-lithiocyclopropenylium ion 10 with the chlorocyclopropenylium ion containing rather bulky alkylamino substituents, the reaction with the 3-chloro-l,2-bis(dimethylamino)cyclopropenyliuin ion 18 took a completely different course i.c. a nucleophilic attack at the amino-substituted carbon of the chlorocyclopropenylium ring, a ring cleavage, then a second nucleophilic attack at the other amino-substituted carbon, followed by protonation. The whole reaction afforded the 1,3-bis-[2,3-bis(diisopropylamino)cyclopropenyliumyl]-l,3-bis(dimethylamino)propenylium trication 20 142 Trication 20 was also prepared by the reaction of two equivalents of l,2-bis(diiso-propylamino)-3-lithiocyclopropenylium perchlorate (10) with l,3-dichloro-l,3-bis(dimethyl-amino)allyl cation 19. 

A MeO bis(pinacolato)diboron adduct ring opens vinyl epoxides and aziridines in the presence of PCy3 and NaOMe in THF giving trans-1,4-hydroxy allyl boronates and trawi-l,4-amino allyl boronates, respectively, in an Sf 2 reaction. Yields range from 71 to 99%. If CuCl is added to the reaction mixture, only the c -l,2-hydroxyboronate is formed in an 5 2 reaction. The results of DFT calculations suggesting the transition state for the reaction on the epoxides is early, while that for the attack on the aziridines is late and that AG is 9-lOkcalmor lower for the aziridine reaction, are consistent with the experimental findings for these reactions. 

Dimethylcimine is dissociatively adsorbed into the dimethylaminyl ion and an H. The H is abstracted by a basic site on the catalyst. The dimethylaminyl ion is stabilized on the surface metal cations. The dimethylaminyl ion attacks the terminal carbon atom of 1,3-butadiene to form amino allylic anion 1. Since the electron density of anion 1 is the highest on carbon atom 4, the H selectively attacks carbon atom 4 to yield the 1,4 addition product. 

Another example of a catalytic asymmetric [3,31-sigma-tropic rearrangement is the catalytic asymmetric amino allylation of aldehydes developed by Rueping and Anton-chick and recently explored by Ren and Wulff (see Scheme 17.23). In this reaction, the homoallyhc amine 96 first condenses with the aldehyde 97 giving imine 98. With the help of an acid catalyst, the i minium ion of imine 98 is formed and the cationic aza-Cope reaction can then ensue giving protected homoallylic amine 99. After treatment... 

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