1,3-Butadienylzinc Trimer Formed via Transmetalation from 1,4-Dilithio-1,3-butadienes: Synthesis, Structural Characterization, and Application in Negishi Cross-Coupling

Abstract

The first well-defined 1,3-butadienylzinc trimers have been synthesized by transmetalation of 1,4dilithio-1,3-butadienes with 1 equiv of ZnBr 2 . Their structures have been determined by single-crystal X-ray structural analysis. Their reaction chemistry has been demonstrated by Pd-catalyzed Negishi cross-coupling with iodobenzenes.

Direct C–C Bond Construction from Arylzinc Reagents and Aryl Halides without External Catalysts

“…Reactions involving functional atoms such as silicon and halogens (see compounds 3ag – k ), as well as those involving heterocycles (see 3al and 3am ), were all successful, suggesting further applicability of this method. Several issues are noteworthy: (1) the reaction of bromide 4a with diarylzinc did not take place under these conditions;9 (2) the monoarylzinc reagent (ArZnCl) was very unreactive, only generating trace amounts of the coupling products; (3) lithium salts facilitated the reaction, although they were not necessary,10 since lithium‐free diphenylzinc was able to react with 1a ,11 albeit with a little lower yield (66 %); (4) magnesium salts were very disadvantageous, because the reaction became quite sluggish when 2a was prepared from the Grignard reagent.…”

Dilithio Spiro Zincacyclopentadienes and Dizinca[10]cycles: Synthesis and Structural Characterization

“…The C–C distances within the ring exhibit clear bond alternation, which are similar to those in 3a . The Zn–C­(sp 2 ) distances [1.981(3), 1.981(3), 1.951(3), 1.956(3) Å] are slightly shorter than those in 3a and comparable to the Zn–C­(sp 2 ) distances in the 1,3-butadienylzinc trimmers 2 . The bite angles of C–Zn­(II)–C ( cis -bonds) are 154.42(14) o and 176.09(15) o , respectively.…”

“…In 2012, we reported the synthesis and structures of 1,3-butadienylzinc trimer 2 by the reaction of 1,4-dilithio-1,3-butadienes (dilithio reagents for short) 1 with 1.0 equiv of ZnBr 2 in Et 2 O (Scheme a) . In this work, we report the synthesis and structural characterization of two other kinds of organozinc metallacycles, dilithio spiro zincacyclopentadienes 3 and dizinca[10]­cycles 4 by the reaction of dilithio reagents 1 with ZnX 2 (X = Cl, Br) in THF (Scheme b).…”

C,C- and C,N-Chelated Organocopper Compounds

“…Although neutral N,N-chelated spiro copper complexes are relatively common, the anionic C,N- or C,C-cheated spiro counterparts are sporadic. As mentioned above, Xi’s group found that the C,C-bidentate ligand is an excellent platform to build up diversified coordination complexes across the periodic table [ 32 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 , 50 , 51 , 52 , 53 , 54 , 55 , 56 , 57 , 58 , 59 , 60 ]. The chelating effect increases the thermal stability of these organometallic species, facilitating isolation and following characterization.…”