Preparation of polyfunctional diorganomercurials and their transmetallation to diorganozincs. Applications to the preparation of optically active secon

Abstract

Two new methods of preparation of functionalized diorganomercurials have been developed. The first method involves a substitution reaction of (ICH,),Hg with zinc-copper reagents FG-RCu(CN)ZnI in THF/DMF at-60°C. Functional groups such as an ester, nitrile, ketone, phosphonate, halide, and boronic ester are tolerated in this reaction. The second method involves a reductive transmetallation between poly-functional organozinc halides and mercurous chloride (Hg,CI,). This very convenient procedure provides a rapid route to various functionalized diorganomercurials in good yields (61-89% yield). The synthetic utility of these mercury organometallics is demonstrated. Their transmetallation with zinc dust (toluene, 8o"C, 3-5 h) affords dialkylzincs which add enantioselectively to aldehydes in the presence of a catalytic amount 120 mol%) of the norephedrine derivative 13. This transmetallation can also be used to prepare stereoselectively (E)-alkenylzinc halides (> 98% El. Addition of CI(H)ZrCp, to (E)-S-chloropentenylzinc bromide in CH,Cl, (2S"C, 1 min) affords a l,l-bimetallic of zinc and zirconium CI(CH,),CH(ZnBr)ZrCp,(CI) which reacts stereoselectively with an aldehyde providing the (Ebdisubstituted olefin (49% yield; 100% El.

2,6-Bis(2-alkylphenyl)-3,5-dimethylphenol as a New Chiral Phenol with C2-Symmetry. Application to the Asymmetric Alkylation of Aldehydes

“…Phenol 3 , aniline 10 , and cinnamaldehyde ( 17 ) were obtained commercially. Aniline derivative 11 and chiral secondary alcohols 18 , 19 , 20 , 21 , 22 , 23 , 25 , and 26 17 are all known compounds, and the spectral data, optical data, and analytical data of these compounds which we obtained agreed with those in the literature.…”

Facile syntheses of homoleptic diarylmercurials via arylboronic acids

“…Hanke has demonstrated that the reaction of mercury(II) acetate with neat phenyl halides at 140°C yields (para-halophenyl)mercuric acetate complexes [13], whereas Rausch and co-workers mercurated ferrocene in glacial acetic acid using mercury(II) acetate [14]. Even more relevant is a Hg-C bond formation observed when mercury(II) acetate is treated with a vinylboronate; the observed product is a bis(vinylated)-mercury(II) complex [15]. Also, as mentioned in the Introduction, Challenger and Richards reported that the reaction of mercuric oxide and arylboronic acids yields diarylmercurials [12], but the products were only characterized by melting point and in one case, elemental analysis.…”

Preparation and reactions of polyfunctional organozinc reagents in organic synthesis

“…29 The zinc insertion shows a remarkable functional group tolerance and most common organic functional groups (i.e. ester,29,35-52 ketone,29,35 cyanide,29,35-43,47,49-52,54 halide, 29,35,43,48,50,52 iV^V-bis(trimethylsilyl)amino group,55 primary and secondary amino groups,56 amide and phthalimide,25,56,57 trialkoxysilyl group,58 sulfoxide,59 sulfide,59 sulfone,59,60 thioester,60 boronic ester,46,48,50 enone,40,53 and phosphate39,61) can be present during the organozinc formation (eq 5). Only hydroxyl groups (deprotonation) or nitro and azide functionalities (inhibition of the zinc insertion) cannot be present in the alkyl iodide.…”