Highly Regio‐ and Stereoselective Iodohydroxylation of Non‐ Heteroatom‐Substituted Allenes: An Efficient Synthesis of 4‐[3′‐Hydroxy‐2′‐iodoalk‐1′(Z)‐enyl]‐2(5H)‐furanone Derivatives

Abstract

An efficient protocol for the highly regioand stereoselective synthesis of 4-(3'-hydroxy-2'-iodoalk-1'(Z)-enyl)furan-2(5H)-one derivatives via selective iodohydroxylation of non-heteroatom-substituted allenes, i.e., 4-allenyl-2(5H)furanones, has been developed. The regio-and stereoselectivity of this reaction may be controlled by the electronic and steric effects of the furanone ring.

Electrophilic Cyclization of 2‐(2′,3′‐Allenyl)acetylacetates with Iodine Using Calcium Hydride as the Base

“…A rationale for the stereoselectivity is shown in Scheme : the regioselective facile interaction of I 2 with the C=C bond close to the nucleophilic group leads to the formation of three‐membered iodonium intermediates int1 and int2 . Due to the steric interaction between the R group and the nucleophilic group, int2 is less favored than int1 13. Subsequent deprotonation and anti ‐attack of the enolic oxygen would afford the 4,5‐dihydrofuran with the Z isomer as the major product.…”

Regio- and Stereoselective Synthesis of Ferrocene-Containing β-Iodoallylic Esters and Ethers from the Iodofunctionalization of Ferrocenylallene with Carboxylic Acids, Phenols, and Alcohols

“…However, owing to the presence of two CC bonds, it is still challenging to control the regio- and stereoselectivities of the reaction. Ma and co-workers have developed a series of halo-/seleno-promoted electrophilic addition reactions, in which a functional group, such as sulfoxide, sulfone, phosphine oxide, sulfide, or selenide, and furanone group are introduced to the allene moiety in order to obtain high regio- and stereoselectivities . Moreover, we recently reported an iodine-mediated iodoamination of ferrocenylallene in moderate to high yields and with high regio- and stereoselectivities, in which the bulky ferrocene group was considered to be the stereochemistry-determining functionality .…”

An Efficient Approach to 2‐Bromoalken‐3‐ols by Regioselective Bromohydroxylation Reaction of Simple Allenes with NBS

“…Halohydroxylations of carbon–carbon double bonds are one of the most important methods for providing 2‐halo‐substituted alcohols1 as two functional groups, that is, X and OH, are introduced into the substrates in one synthetic operation. During the last 10 years we have developed highly regio‐ and stereoselective halohydroxylation (X = Cl, Br, I) reactions of allenyl sulfoxides,2a,2b sulfones,2c phosphane oxides,2d,2e sulfides,3a,3b selenides,3c and furanones 4. The reactions of sulfoxides, sulfones, and phosphane oxides afforded ( E ) products, whereas those of sulfides, selenides, and furanones afforded ( Z ) products 5…”