Amines allylic, reductive cleavage

Primary ally lie amines1 In the presence of this catalyst, allylic chlorides or acetates react with sodium p-toluenesulfonamide in THF/DMSO (80 20) to form the corresponding allylic sulfonamide in 60-85% yield. The products are converted into primary allylic amines on reductive cleavage (sodium naphthalenide). 

Subsequently, Julia, Uguen and Callipolitis104 105 used both lithium metal in ethyl-amine and sodium amalgam in ethanol to effect reductive cleavages of j8-hydroxysulphones or of allylic sulphones. The latter reaction is part of a synthetic sequence for the construction of alkenes that has been used with some considerable success... 

Ally lie amines.1 The trimethylsilylisoxazolidines formed on cycloaddition of vinyltrimethylsilanes with nitrones (12, 566) are converted on reductive cleavage of the N—O bond and concomitant Peterson elimination of (CH3)3SiOH into allylic amines. 

Allylie and homoallylic secondary amines were prepared by reductive cleavage of isoxazolidines formed by dipolar cycloaddition of nitrones with vinyl- and allyl-silanes, respectively (Scheme 27).65 The approach is useful because the geometry of the alkene can be controlled by choosing the conditions of elimination. Azaphospha macrocycles have been prepared from diethylenetriamine. 

A synthesis of Agelastatin A by Weinreb and co-workers featured the use of a 13 bis[2-(trimethylsilyl)ethylsuifonyl] sulfodiimide 137 2 as an enophile in a two-step allylic amination reaction [ heme 8.137]. The initial ene reaction produced a dipolar intermediate 1373 that underwent a [2,3] Sigmatropic shift to afford the SES-protected allylic amine derivative 137,4. Reductive cleavage of the N-S bond followed by cleavage of the Boc group with trifluoroacetic acid gave the sulfonamide 1373 in 50-60% overall yield. Final deprotection of the SES group with TBAF returned the desired amine 137,6 in 90% yield. 

Reductive cleavage is facilitated when the anions are stabiUzed by resonance or by an electronegative atom. As expected, therefore, bonds between heteroatoms or between a heteroatom and an unsaturated system which can stabilize a negative charge by resonance, are particularly easily cleaved. Thus allyl and benzyl ethers and esters (and sometimes even allyl or benzyl alcohols) are readily cleaved by metal-amine systems (or by catalytic hydrogenation). This type of reaction has... 

The synthesis began with (+)-citronellal 4, each enantiomer of which is commercially available in bulk. After protection and ozonolysis, the first singly-aminated stereogenic center was installed by enantioselective, and therefore diastereoselective, addition of 5 to the azodicarboxylate 6, mediated by the organocatalyst 7. Reductive cleavage of the N-N bond followed by acetal methano lysis converted 8 to 9. Ionization followed by allyl silane addition then delivered 11, having the requisite axial alkyl branch. 

The stability of the pyrimido[4,5- pyrimidin-2(lf/)-one core to oxidative and reducing conditions is illustrated further in the preparation of a range of l-(2-aminoethyl) derivatives by oxidative cleavage of a 1-allyl species and reductive amination of the resulting aldehyde (Scheme 39) <2002W002/066482>. 

The ease of reduction decreases in the order benzyl > allyl > phenyl > alkyl. Utilizing these differences in reducibility Horner etal. 505 J opened an elegant route to unsymmetrically substituted amines RjR2R3N by combination of alkylation and cathodic cleavage. 

The following reactions proceed with the participation of the allylic boron system (i) allylboration and protolytic cleavage of organic compounds with multiple bonds, (ii) allylboron-alkyne condensation,598 599 (iii) reductive mono-and trans-a,a -diallylation of nitrogen aromatic compounds, (iv) disproportionation processes between tribut-2-enylborane and BX3 (X = C1, Br, OR, SR). Allylboration of carbonyl compounds, thioketones, imines, or nitriles leads to the homoallylic alcohols, thiols, or amines (Equations (136) and (137). It is most important that 1,2-addition to aldehydes and imines proceeds with high diastereoselectivity so that ( )-allylic boranes and boronates give the anti-products, while -products are formed preferentially from (Z)-isomers. 

Photochemical Fe(CO)5-induced rearrangement of silylated allyl amine 9 gave N-silylated enamine 1015, which on subsequent Cu-catalyzed cyclopropanation by methyl diazoacetate afforded cyclopropane derivative 11. The use of an optically active catalyst gave an asymmetric induction of 56% ee for the cis isomer and 20% ee for the trans isomer. Further acid-induced ring cleavage afforded the -formyl ester 12, whereas reduction and desilylation produced aminocyclopropane carboxylic acid 13 (equation 2). 

These amines can be deprotected under reduction conditions (Pd-C/R0H/HC02NH4 or Na/NH3). The allyl amines can be deprotected by oxidative cleavage with ozone (dimethyl-sulfide work up) or with KMn04 in acetone. 

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