A - benzyl amines

Novolaks. Novolak resins are typically cured with 5—15% hexa as the cross-linking agent. The reaction mechanism and reactive intermediates have been studied by classical chemical techniques (3,4) and the results showed that as much as 75% of nitrogen is chemically bound. More recent studies of resin cure (42—45) have made use of tga, dta, gc, k, and nmr (15). They confirm that the cure begins with the formation of benzoxazine (12), progresses through a benzyl amine intermediate, and finally forms (hydroxy)diphenyknethanes (DPM). 

Since amines react more readily than alcohols in noncatalyzed reactions with anhydrides, the reaction is more difficult and initially required stoichiometric catalyst loadings [107], but could be performed in a catalytic sense with an O-acylated azlactone as acylating agent, which does not react with a benzylic amine at —50°C, but is capable of acylating the catalyst [108, 109]. Depending on the buUdness of the substrate, selectivities ranged from S = 11 to 27 (s = [ enantiomer l]/[ enantiomer 2])-... 

The Sommelet-Hauser rearrangement formally involves the conversion of a benzyl ammonium salt such as 76 into a benzyl amine (e.g., 79). 

In the hydrogenolytic asymmetric transamination between a benzylic amine and oxalacetic acid the Schiff s base was hydrogenated in ethanol over palladium, but alanine rather than aspartic acid was the... 

Aryl benzyl ethers are cleaved more easily than are alkyl benzyl ethers. The presence of an amine hinders the hydrogenolysis of alkyl benzyl ethers but has no effect on the cleavage of aryl benzyl ethers. - Because of this the benzyl ether is selectively hydrogenolyzed in compounds containing both a benzyl amine and an aryl benzyl ether (Eqn. 20.24)55 but the benzyl amine is selectively cleaved in compounds having both a benzyl amine and an alkyl benzyl ether (Eqn. 20.25).53,54,56... 

Similar rearrangements also occur in the case of sulfur analogs. Since the product of a Sommelet-Hauser rearrangement is a benzylic tertiary amine (or sulfide), just as the starting material was a benzylic amine (or sulfide), the process can be repeated and is a unique method to move substituents around the periphery of aromatic rings (Scheme 109). 

An early example of this strategy is the palladium black catalyzed conversion of (Z)-2-buten-l,4-diol with primary amines (cyclohexyl amine, 2-ammoethanol, //-hexyl amine, aniline) at 120°C to give A-substituted pyrroles in 46-93% yield [144]. Trost extended this amination to the synthesis of a series of A-benzyl amines 235 from the readily available a-acetoxy-cx-vinylketones 234 [145]. This methodology allowed for the facile preparation of pyrrole-fused steroids. 

In the same way, direct comparison with other groups15 shows that the simple methoxy director is less powerful than a sulfonamide 81 or a benzylic amine 82, but more powerful than F, CF3, NR2, or (CH2)2NR2. 

Due to the steric environment presented by the ortho piperidine group, displacement of the benzylic alcohol proved problematic. Although displacement of the alcohol could be effected when R was less sterically imposing, this route was less desirable due to the need to tolerate a benzylic amine during introduction of the piperidine fragment. The most efficient protocol for introduction... 

Eschweiler illustrated in his report several examples, including a benzyl amine and diamines such as piperazine and ethylenediamine, and noted the complete methylation of the amines, without quatemisation.1... 

The nucleophilic substitution reaction installing a benzylic amine on mono-chlorotriazine derivatives [143] was performed under the action of MW irradiation, enabling aminotriazine compounds to be obtained very quickly with good yields in very short reaction times compared with conventional heating (15 min instead of 2 days) (Eq. 58) ... 

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