Ring Expansion Fluorination of Unactivated Cyclopropanes Mediated by a New Monofluoroiodane(III) Reagent

Abstract

Herein, we report anew strategy for carbon À carbon bond scission and intramolecular ring expansion fluorination of unactivated cyclopropanes,w hichw as accomplished with an ew hypervalent fluoroiodane(III) reagent 1.T his novel method delivers medicinally relevant 4-fully substituted fluoropiperidines in moderate to high yields with excellent regioand diastereoselectivity.Reagent 1,which has an N-acetylbenziodazole framework, was readily synthesized via three steps in 76 %o verall yield and was characterized by NMR spectroscopya nd X-ray crystallography.O wing to the presence of as econdary I•••O bonding interaction between the l 3 -iodane atom and the carbonyl oxygen of the acetyl group of the Nacetylbenziodazole framework, 1 has excellent stability and can be stored at ambient temperature for 6months without any detectable decomposition. Density functional theory calculations and experimental studies showed that the reaction proceeds via acarbocation intermediate that readily combines with afluoride ion to generate the product.

Updates on hypervalent-iodine reagents: metal-free functionalisation of alkenes, alkynes and heterocycles

“…DFT studies revealed that the mechanism proceeds through a carbocationic intermediate (Scheme 47). 105…”

“…DFT studies revealed that the mechanism proceeds through a carbocationic intermediate (Scheme 47). 105 As per the suggested mechanism, initially, the hypervalent species The Wengryniuka group in 2021, reported an efficient method that provides access to functionalised chromanes (78) from primary, secondary, and tertiary alcohols via cyclisation followed by iodonium salt formation (Scheme 49). 106 The He group reported an effective method for the aminolactonisation of unactivated alkenes (79) via aryl-iodine catalysis, in which diverse amino lactones (80) are constructed in a short time using HNTs 2 as the compatible nitrogen source.…”

Ring Expansion Fluorination of Unactivated Cyclopropanes Mediated by a New Monofluoroiodane(III) Reagent

“…ORTEP drawings of 3fand 3s with thermal ellipsoids at 50 %p robability. [25] Angewandte Chemie Forschungsartikel substrates 2s' ', 2t' ' were tried, the reaction still proceeded well and afforded desired products 3s' ', 3t' ' in 86 %and 87 %yield, respectively.T he structures and stereochemistries of these products were established by 1 HNMR and nuclear Overhauser effect experiments (see the SI for details). Furthermore,weconfirmed that the cis isomer was the major product by means of single-crystal X-ray diffraction analysis of 3s (Figure 3).…”

Convenient Synthesis of Benziodazolone: New Reagents for Direct Esterification of Alcohols and Amidation of Amines

“…Benziodazolone compounds 2 , nitrogen analogs of benziodoxolones, are also known and offer the possibility of fine-tuning the reactivity by modifying the substituent on the nitrogen atom [ 20 , 21 , 22 , 23 ]. Thus, a number of reagents of 2 with various nitrogen-containing ligands and functional groups have been developed [ 24 , 25 , 26 , 27 , 28 ]. For example, benziodazolone compounds 2 supported by various ligands are known as atom-transfer reagents and can act as very effective electrophilic reagents for a variety of substrates, including azidation [ 20 ], alkynylation [ 24 ], and trifluorothiomethylation reagents [ 25 ].…”

“…For example, benziodazolone compounds 2 supported by various ligands are known as atom-transfer reagents and can act as very effective electrophilic reagents for a variety of substrates, including azidation [ 20 ], alkynylation [ 24 ], and trifluorothiomethylation reagents [ 25 ]. Very recently, Zhang and coworkers investigated the synthesis and structural characterization of a stable fluorobenziodazolone compound and demonstrated that the novel reagent can efficiently perform ring-extended fluorination reactions for various three-membered ring compounds [ 26 ]. In addition, benziodazolones 3 are also capable of working as oxidants in dehydrogenative coupling reactions between various two-component molecules [ 27 ].…”