A Very Simple Synthesis of Chloroalkenes and Chlorodienes by Selective Suzuki Couplings of 1,1‐ and 1,2‐Dichloroethylene

Abstract

Chloroalkenes, important building blocks for cross-coupling reactions, are prepared in one step by the Suzuki reaction of 1,1-dichloroethylene and 1,2-dichloroethylene with alkenyl-and arylboronic acids. Under the proper reaction conditions, it is possible to obtain the monocoupling reaction to provide the corresponding chloroalkenes with good yields. This method represents an excellent route for the preparation of chloroalkenes and chlorodienes from commercially available starting materials.

Various Entries to Vinyl Chloride Derivatives and their Applications in Total Synthesis of Natural Products

“…In sharp contrast with the cross-coupling of gem-dichloroolefins, the use of large bite angles phosphines 18 such as XantPhos (12) or DpePhos (13) did not improve the yield of the reaction and even favored the formation of alkyne 20 (Scheme 8), supposedly by a syn-b-elimination of the chloride atom. However, after extensive optimization, we were delighted to find that Fu's conditions [Pd 2 (dba) 3 and phosphine P(tBu) 3 ·HBF 4 ] 33 allowed us to obtain the desired chloroolefin 19 with a 91% yield and with full retention of the configuration of the double bond.…”

“…Thus we reinvestigated our methodology, and, gratifyingly, after many trials on our fragments 21 and 22, we eventually found that switching from XantPhos (12) to DpePhos (13) and removing KF accomplished an effective cross-coupling furnishing 31 with a strongly improved yield (87%, Scheme 12). Then, after saponification of the two ester functions of 31, we obtained seco-acid 32, ready for the macrocyclization step.…”

Bis(1,1-dimethylethyl)[2′,4′,6′-tris-(1-methylethyl)[1,1′-biphenyl]-2-yl]-phosphine and Dicyclohexyl[2′,4′,6′-tris(1-methylethyl)[1,1′-biphenyl]-2-yl]phosphine

“…5 The second example shows an application for the synthesis of chlorodienes. 6 Coupling with a Pd/X-Phos catalyst has also been applied for the preparation of C-15 vindoline analog. 7 Palladium complexes employing X-Phos as a ligand have been used for the stepwise double substitution of 1,1-dichloro-1-alkenes by using the Negishi coupling (eq 5).…”

Facile synthesis of unsymmetrical 1,1-diaryl-2,2-difluoroethenes via stepwise coupling of 1,1-dibromo-2,2-difluoroethenes

“…A straightforward synthesis of unsymmetrical 1,1-diaryl-2,2-difluoroethenes might be achieved simply with two reactivity-controlled coupling reactions, starting from 1,1-difluoro-2,2-dihaloethenes. However, there are only a few examples of the monoarylation of symmetric gem-dihaloethenes [7], because this type of selective reaction requires steric and/or electronic effects of vinylic substituents [8]. Although the monoarylation of symmetric gem-dichloroethenes has been reported, the low reactivities of their chlorine substituents might prevent a second arylation toward diarylated ethenes.…”