A synthesis of (+)-pederin. The metallated dihydropyran approach

Article abstract of DOI:10.1016/S0040-4039(00)97415-X

The addition of a 6-lithio-3,4-dihydro-2H-pyran to a methyl oxamate ester in the presence of TMEDA is a key step in the synthesis of a masked 1,2,3-tricarbonyl moiety used to construct the N-(1-alkoxy-1-alkyl)-amide bridge of the potent cytotoxic agent pederin. A Pd(0)-catalysed stannylation of an O-trifluoromethylsulfonyl ketene acetal provides an efficient synthesis of the 6-(trimethylstannyl)-3,4-dihydro-2H-pyran which transmetallates to the lithium derivative on treatment with n-BuLi.