Organocopper complexes aldehydes

High stereoselectivity was also observed in the reaction of organocopper reagents 215 with the aldehyde moiety of (774-diene)Fe(CO)3 complexes 214 (Scheme 98).491... 

Diastereoselective addition in Et20/HMPT (1 1) leads to the (5)-aldehyde with an enantiomeric excess of 40%, whereas in -hexane the (2 )-aldehyde is formed with 80% ( ) enantiomeric excess. The (2 )-configured aldehyde is also obtained in benzene and in dichloromethane, but with lower ee values of 50% and 25%, respectively. Inverse results were obtained with a chiral oxazolidine prepared from ( )-cinnamaldehyde and (+)-ephedrine. Here, the (5)-aldehyde with ee = 79% is formed in -hexane, and the (7 )-aldehyde in Et20/HMPT (1 1) with ee = 50% [703], This result may be due to different structures of the organocopper reagent, and hence of the diastereomorphic activated complexes, in nonpolar solvents ( -hexane, benzene, dichloromethane) and in EPD solvents (Et20/HMPT) [703]. 

Discussed in this chapter, for the most part, are documented cases where complexes derived fiom (one or more equivalents of) a Grignard or organolithium reagent, in combination with a copper(I) salt, have been used to add to an aldehyde, ketone, imine, amide or nitrile moiety. In the majority of examples, the key issue is one of stereocontrol. Hence, where available, data within the organocopper manifold versus those for other organometallic reagents are provided for comparison. 

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