Trichloroacetimidic esters, Overman

Liebigs Ann Chem 654 180 1962]. It is readily converted into its trichloroacetimidate esters by reaction with ally lie alcohols in CH2CI2, in the presence of DBU at to ambient temperatures [Anderson Overman J Am Chem Soc 125 12412 2003, Kirsch et al. Org Lett 9 911 2007] similarly prepared trichloroacetimidates of allylic alcohols were shown to undergo ether-directed Pd(II)-catalysed aza-Claisen rearrangements [Jamieson Sutherland Tetrahedron 63 2132 2007], and bis-trichloroacetimidates from 2-aminopropane-l,3-diols yielded dihydrooxazines through an acid catalysed cychsation [Rondot et al. Org Lett 9 247 2007],... 

In some cases, the mercury(II)- and palladium(II)-catalysed allylic Overman rearrangement of trichloroacetimidates can be accomplished under mild conditions at room temperature or even much lower temperature. For example, the trichloroacetimidic ester of geraniol 12 is converted to linalyl trichloroacetamide 13 when treated with 0.2 equiv of mercuric trifluoroacetate at room temperature for 10 min. This catalytic... 

The Overman esterification is a palladium-catalyzed formation of enantioenriched allyl esters from carboxylic esters with primary allyl imidates. From a mechanistic point of view, it is related to the Tsuji-Trost reaction. It proceeds under quite mild conditions with high enantiomerically access if the COP ([Ti -(5)-2-(4-methylethyl)-oxazolinylcyclo-pentadienyl]-(T] -tetraphenylcyclobutadiene)cobalt) complex is used. For example, Kirsch and co-workers used the Pd-catalyzed Overman esterification " in their approach to 1,3-polyols starting from (Z)-allylic trichloroacetimidates to build up the stereogenic centers. By choice of the required enantiomer of COP-OAc catalyst, every possible diastereoisomer is accessible in high stereoselectivity (Experimental Procedure below). 

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