Photochemical Synthesis of Phosphinolines from Phosphonium−Iodonium Ylides

Phenoxaphosphonium Mixed Ylides in Ring Expansion Reaction

Treatment of mixed phosphonium-iodonium ylides featuring a six-membered phenoxaphosphonium fragment with aqueous tetrafluoroboronic acid induces a rearrangement, resulting in expansion of the phosphacycle and oxidation of the phosphorus atom. The target difficult-to-access dibenzo[b,f][1,4]oxaphosphepine oxides (3 examples) were isolated in excellent yields (up to 95%) as mixtures of stereoisomers. Hydrolysis of a five-membered mixed ylide, a dibenzophosphole derivative, predominantly preserves the phosphole system with cycle expansion occurring as a side process.

Visible-Light-Induced Annulation of Iodonium Ylides and 2-Isocyanobiaryls to Access 6-Arylated Phenanthridines

A 1,2,3,5-tetrakis(carbazol-9-yl)-4,6-dicyanobenzene (4-CzIPN)-photocatalyzed cascade arylation/cyclization reaction of 2-isocyanobiaryls and iodonium ylides was established for the synthesis of 6-arylated phenanthridines. This is the first example of employing iodonium ylides as aryl radical sources in a visible-light-induced radical cascade cyclization reaction.

Blue LED Irradiation of Iodonium Ylides Gives Diradical Intermediates for Efficient Metal-free Cyclopropanation with Alkenes

A facile and highly chemoselective synthesis of doubly activated cyclopropanes is reported where mixtures of alkenes and β-dicarbonyl-derived iodonium ylides are irradiated with light from blue LEDs. This metal-free synthesis gives cyclopropanes in yields up to 96 %, is operative with cyclic and acyclic ylides, and proceeds with a variety of electronically-diverse alkenes. Computational analysis explains the high selectivity observed, which derives from exclusive HOMO to LUMO excitation, instead of free carbene generation. The procedure is operationally simple, uses no photocatalyst, and provides access in one step to important building blocks for complex molecule synthesis.

CIDNP as a tool to unveil the reaction mechanism: interaction of mixed phosphonium–iodonium ylide withp-methoxyphenylacetylene

In situ acquisition of the reaction between benzoyl phosphonium–iodonium ylide and p-methoxyphenylacetylene in an NMR spectrometer reveals the CIDNP effect in ³¹P and ¹H NMR spectra of major products, substituted furan (emission) and phosphonium salt (enhanced absorption). The mechanism of products formation via radical pairs is discussed.

CIDNP in ³¹P NMR spectra of major products in the course of the reaction between phosphonium–iodonium ylide and p-methoxyphenylacetylene reveals the mechanism of products formation via radical pair.

Crystal structure of 2-(4-methylphenyl)-2-oxo-1-(phenyliodonio)-1-(triphenylarsonio)ethanid tetrafluoroborate solved from X-ray powder data

The crystal structure of 2-(4-methylphenyl)-2-oxo-1-(phenyliodonio)-1-(triphenylarsonio)ethanid tetrafluoroborate, C33H27AsIO+BF4 –, was solved and refined from laboratory X-ray powder diffraction data in combination with a DFT calculation (CoK α1, a=24.427(2) Å, b = 13.3412(18) Å, c=22.399(2) Å, β = 119.49(2)°, S.G. C2/c, R p/R wp = 0.030/0.039). The main features of the C33H27AsIO+BF4 – structure are similar to those reported previously for arsenium and phosphorous organic compounds. The distinctive features are short I … O and I … F (2.743(19) and 2.916(17) Å, respectively) intermolecular contacts, also observed previously in the same type of compound, refined from single crystal data.