Rhenium-catalyzed Carboesterification Of Alkenes With Hypervalent Iodine Reagents Via Decarboxylation

The metal Rhenium is one of the early transition metals, while Manganese （they sharewith the same VII group） plays a vital role in catalyzing reactions such as radical and singleelectron transfer （SET） ones. Nowadays, both of the two elements don’t have caught so manyresearchers’ attention. However, from the previous result we know that the rhenium catalystshave a special activity and selectivity in the process of establishing C-C and C-X （X=O, N, Si,B, etc.） bonds. Herein, we have developed a new reaction which utilizing rhenium catalyst(ReBr（CO）₅, ReCl（CO）₅and Re2（CO）₁₀) and hypervalent iodine reagents （PhI（OAc）₂and itsanalogues） to accomplish the carboesterification of alkenes （styrene and its analogues andcinnamate methyl and stilbenzene and4-vinyl-1,1’-biphenyl）, in other words, we haveintroduced the alkyl and ester groups onto the double bond simultaneously.Part1: Whether hypervalent iodine derivatives such as PhI（OAc）₂as the source ofaliphatic group or PhI（OCOPh）₂as the source of aromatic group can constitute ester groups.Besides, aliphatic chain or aromatic substituent comes from their corresponding carboxylationgroups with a loss of CO2molecule. The co-existed ester and decarboxylated groups can belinked onto the styrene’s double bond with good regio-selectivity.Part2: With the in-depth research on reaction mechanism, it is to be possible that abi-functionalization process which containing both radical and ionic intermediates could takeplace during the reaction.Part3: Styrene derivatives can be varied for17alternatives, and many substituentgroups can be tolerated such as halo, alkyl and methoxy groups, while some other alkenederivatives such as4-vinyl-1,1’-biphenyl, cinnamate methyl and stilbenzene are alsoworkable. Furthermore,8hypervalent iodine derivatives （their carboxylation groups variedfrom aliphatic to aromatic ones） are also applicable here.It is worth noting that in organic synthesis the ordinary application of hypervalent iodinederivatives are their oxidant nature rather than the source of ester groups or alkyl chains,besides, the utilization of rhenium catalysts in such a decarboxylation and esterificationaddition of C-C double bond is unprecedented. Though the decarboxylation process ofhypervalent iodine could occur under a relatively harsh condition such as high temperature or the radiation of high pressure mercury lamp, this process could be undertaken in a mildcondition and produced little deleterious waste. The addition process of double bond can beregioselective.