Portal de Periódicos da CAPES

Sulfoxides as Stereochemical Controllers in Intermolecular Heck Reactions

2001; Wiley; Volume: 7; Issue: 18 Linguagem: Inglês

10.1002/1521-3765(20010917)7

1521-3765

Nuria Díaz Buezo, Juan Carlos de la Rosa, Julián Priego, Inés Alonso, Juan C. Carretero,

Asymmetric Synthesis and Catalysis

The use of the sulfinyl group as a chiral auxiliary in intermolecular Heck reactions of cyclic alkenes with iodoarenes has been studied (see scheme). High asymmetric inductions were obtained by use of the palladium-chelating o-(N,N-dimethylamino)phenylsulfinyl group. Both Heck and double Heck reactions can be performed with this chiral auxiliary. The final reductive elimination of the sulfoxide gave 1-aryl-substituted or 1,3-diaryl-substituted cyclic compounds in high enantiomeric purity. The study of a variety of substituted sulfoxides as chiral auxiliaries in intermolecular Heck reactions of sulfinyldihydrofurans and sulfinylcyclopentenes with different iodoarenes is reported. In the presence of [Pd(OAc)2]/Ag2CO3 and a bidentate phosphine ligand, synthetically useful yields and asymmetric inductions were obtained. By far the best diastereoselectivities were obtained by the use of the palladium-coordinating o-(N,N-dimethylamino)phenylsulfinyl group. By final removal of the chiral auxiliary, these sulfoxide-stereocontrolled asymmetric Heck processes were applied to the enantioselective synthesis of 1-aryl-substituted and 1,3-diaryl-substituted dihydrofurans and cyclopentenes. Se ha abordado el estudio de una amplia variedad de sulfóxidos como auxiliares quirales en reacciones de Heck intermoleculares de sulfinildihidrofuranos y sulfinilciclopentenos con yodoarenos. Elevados rendimientos e inducciones asimétricas apreciables se obtuvieron utilizando [Pd(OAc)2] como catalizador, Ag2CO3 como base y una fosfina bidentada como ligando. Con gran diferencia, las mejores diastereoselectividades se obtuvieron utilizando un sulfóxido con capacidad para coordinarse con el átomo de paladio: el grupo o-(N,N-dimetilamino)fenilsulfinilo. Tras eliminación final del auxiliar quiral, estas reacciones de Heck asimétricas controladas por el grupo sulfinilo se han aplicado a la síntesis enantioselectiva de dihidrofuranos y ciclopentenos 1-aril y 1,3-diarilsustituidos.