I(py)₂BF₄, a New Reagent in Organic Synthesis: General Method for the 1,2‐Iodofunctionalization of Olefins

Abstract

plitudes [I> 2cr(I)] together with Friedel reflections; R =0.066. N-La-N angles ofthe diagonals 175.0--17X.5": La-N 2.734-2.831 A (mean value 2.770 A): intra-2 N-N 2.772-2.976 A (mean value 2.917 A); inter-2-

Transferring iodine: more than a simple functional group exchange in organic synthesis

“…In this regard, tetrafluoroboric acid is very useful due to the low nucleophilic character of the BF 4 ¹ counteranion. When simply the reagent, the acid and the alkene are mixed at low temperature, a clean, regio-and stereoselective iodofluorination takes place [3,4], as also depicted in Scheme 1 for the case of 1c.*Lecture presented at the 5th International Conference on Heteroatom Chemistry (ICHAC-5), London, Ontario, Canada, 5-10 July 1998, pp. 369-512.…”

“…Initial efforts were devoted to the development of a methodology that can be useful to accomplish vicinal iodofunctionalization of an alkene. Thus, when the reagent is mixed in CH 2 Cl 2 with an alkene and a nucleophile the corresponding products derived from the addition of an iodine atom and the nucleophile across the double bond are formed, for instance MeOH for 1a, in Scheme 1 [3]. Usually, an acid is required to neutralize the supply of pyridine molecules from the iodinating reagent, avoiding the formation of adducts, such as 1b, that incorporate pyridine as a nucleophile through a competition process for the capture of the intermediate iodonium ion.…”

Halogen-Bonded Co-Crystals of Aromatic N-oxides: Polydentate Acceptors for Halogen and Hydrogen Bonds

“…Knowledge of R XB values provides an opportunity to roughly estimate the strengths of XB complexes. For example, the X···N distances in bis(pyridine)iodonium(I) tetrafluoroborate constitute an R XB value compounds are classified as halogen bonds of covalent nature [14]. Carefully designed nitrogen compounds are successfully utilized as molecular building blocks engaging in (N−X−N)⁺X − XBs to construct supramolecular structures resembling metal coordination frameworks [15].…”

IPy2BF4‐Mediated Rearrangements of 1,2‐Difunctionalized Compounds and Olefins

“…[12,15] General procedure for the rearrangement reaction of 1,2-difunctionalized compounds 3 to give aldehydes or ketones 1: General procedure for the rearrangement reaction of 1,2-difunctionalized compounds 3 to give acetals 4 or aldehyde 1 e: A solution of IPy 2 BF 4 (0.41 g, 1.1 mmol) in dry CH 2 Cl 2 (2.5 mL) was prepared under nitrogen and treated with dry BF 3 ·OEt 2 (3 mL of a 0.4 m solution in the same solvent, 1.1 mmol) and methanol (46 mL, 1.1 mmol) at room temperature. A solution of the corresponding compound 3 (0.5 mmol) in CH 2 Cl 2 (2 mL) was then added at the same temperature.…”

“…IPy 2 BF 4 -mediated rearrangement reactions of olefins: tandem iodofunctionalization/rearrangement reactions: Bearing in mind that all the alkoxy-substituted iodides used as starting materials in the previous sections can be easily obtained from olefins by the well-established iodofunctionalization reaction mediated by the reagent IPy 2 BF 4 , [15] we believed that we could develop a tandem iodofunctionalization/rearrangement method to transform olefins into acetals directly. The scope of the reactions described previously in this paper would be considerably extended if this tandem process could be achieved.…”