Aminoacetoxylation, alkene

The first example of intermolecular Pd-catalysed aminoacetoxylation of alkenes, such as (52), with phthalimide as the nitrogen source and PhI(OAc)2 as the stoichiometric oxidant and source of acetate has been reported. The reaction is highly regio- and diastereo-selective mechanistic studies revealed that the reaction proceeds... 

Liu G, Stahl SS (2006) Highly regioselective Pd-catalyzed intermolecular aminoacetoxylation of alkenes and evidence for cis-aminopalladation and SN2 C-O bond formation. J Am Chem Soc 128 7179-7181... 

A very interesting Pd"aminoacetoxylation reaction of alkenes was recently developed jointly by the Sorensen and Lee groups [60]. In a representative example, treatment of 75 with Pd(OAc)2 and PhI(OAc)2 provides oxazohdinone 76 in 65% yield with >20 1 dr (Eq. (1.33)). This transformation is heheved to proceed via a Pd"/Pd catalytic cycle that is initiated by antLatninopaUadation of the alkene to afford 77. The intermediate Pd complex is then oxidized by PhI(OAc)2 to alkyl Pd intermediate 78, which undergoes C—O bond-forming reductive elimination to afford 76. 

In recent years a series of aminoacetoxylation reactions have been reported, which all appear to follow the same concept (Scheme 4.7). These approaches were initiated within an investigation on direct aminoacetoxylation of alkenes by Sorensen [29]. This protocol provides a convenient approach to various pyrrolidines, piperazines, lactams, oxazolidin-2-ones and oxazinan-2-ones containing a... 

An important study by Stahl and liu on intermolecular aminoacetoxylation of aUyl ethers revealed that this type of transformation could be carried out intermolecularly with complete regio- and stereoselectivity. The reaction was developed for terminal alkenes 176, and 13 examples of allyl ethers were presented with products 177 obtained in yields from 30 to 84% [119]. It suffers from the requirement of a twofold excess of alkene, but the demonstration of a first example of this type of reaction is a striking accomplishment (Scheme 16.47). 

The authors also used this transformation to investigate the overall stereochemical course, and in particular the pathway of oxidative intermolecular aminopalladation. Within this detailed mechanism, they arrived at the conclusion of an overall sequence of syn-aminopalladation and anti-C-O bond formation to explain the observed product stereochemistry for aminoacetoxylation of an internal alkene. This final result matches with the observed stereochemistry from related intramolecular cases [87]. 

In recent years, a number of novel palladium-catalyzed diaslereoselective alkene difunctionalization reactions, such as aminohalogenation [34], aminoacetoxylation [35], aminofluorination [36], and diamination [37], have been studied intensively by the combination of other reactions with an amino- or oxopaUadation reaction. In some of these transformations, a Pd(IV) species is believed to be the key intermediate (Scheme 6.21). 

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