Interaction of an allene with polyvalent iodine derivatives. Preparation, x-ray molecular structure, and some reactions of phenyl(2,2-dimethyl-4-(diethylphosphono)-2,5-dihydro-3-furyl)iodonium salts

The Halogen Bond

“… Short and directional XBs existing in halonium salts. Phenyl[2,2-dimethyl-4-(diethylphosphono)-2,5-dihydro-3-furyl]iodonium perchlorate (VOYXEM 108 ): one oxygen of the phosphonate residue and one oxygen of the perchlorate anion work as XB acceptors. [2-Ethoxy-2-oxo-1-(triphenyl-λ 5 -phosphanylidene)ethyl]phenyliodonium tetrafluoroborate (IWUKEQ 109 ): the carbonyl oxygen of the carbethoxy residue and a fluorine atom of the fluoroborate anion work as XB acceptors.…”

Alkenyliodonium salts

“…Thus salt 40a was obtained by the reaction of diethyl 1-methoxy-4methylpenta-2,3-dien-2-ylphosphonate (41) with 2 equivs of iodosylbenzene in the presence of boron trifluoride diethyl etherate. 62 The respective perchlorate 40b was obtained in 48% yield upon treatment of the reaction mixture with a saturated aqueous solution of LiClO 4 . The salt 40 is also formed in the reaction of the allene 41 with a system PhIF 2 ± BF…”

“…Several of them were deduced on the grounds of chemical transformations of these intermediates in reactions with various organic substrates. For example, the reactions with alkynes, aromatic compounds and enol silyl ethers gave rise to iodonium salts 41,58,59,62,82 and b-diketones. 41 Fluoro(hydroxy)iodanylarene sulfonates 16 react stereoselectively with terminal alkynes to form (E)-[b-(sulfonyloxy)alk-1-enyl](aryl)iodonium sulfonates 78; 105,109 the structure of one of these compounds was proved by X-diffraction analysis.…”

“…Thus the reactions of compound 40b with nucleophiles lead to the corresponding cyclic adducts through a two-step addition ± elimination process and/or reductive elimination following attack by a nucleophile on the iodine atom (Scheme 2). 62 Perchlorate 40b reacts with sodium azide in acetonitrile to give vinyl azide 149 in nearly quantitative yield. The reactions of compound 40b with sodium methoxide and sodium ethoxide in the respective alcohol afford vinyl ethers 150 in 83% and 91% yields, respectively.…”

Alkynylations and Vinylations

“…In addition, these salts also undergo solvolysis and fragmentation: the solvolysis of (4-tert-butylcyclohex-1-enyl)phenyliodonium tetrafluoroborate (118) in MeOH at 25 °C provided the solvolysis product 119, iodobenzene and coupling product 120 (equation 52) 21 . Due to their excellent capability to produce alkenyl carbocations under very mild conditions, alkenyl(aryl)iodonium salts have been used as alkenylating reagents in reactions with various heteroatom nucleophiles including boron 221,222 , oxygen [223][224][225] , nitrogen 203,[224][225][226] , halides 203,213,224,225,[227][228][229] , silicon 223 , sulfur 203,213 , and phosphorous 225,230 (Scheme 23). Different mechanistic pathways such as S N 1, S N 2, ligand coupling, and Michael addition-elimination have been proposed in alkenylation of heteroatom nucleophiles.…”