Hypervalent Iodine Compounds with Tetrazole Ligands

Abstract

Hypervalent iodine compounds with two I-N bonds, containing 5-substituted tetrazoles as the ligands PhI(NCR) (R = CH, CH, and 4-CHCH), were synthesized from PhI(OCCF) or PhICl and the corresponding tetrazole potassium salts. Alternatively, PhIO was reacted with the free tetrazoles, and the reactions afforded either PhI(NCR) or, in most cases, μ-oxo- or oligomeric compounds with several I and O atoms in the backbone and two terminal tetrazole groups. The isolated compounds were reasonably stable in the solid state as well as in solution at room temperature but explosive at elevated temperatures (135-180 °C depending on the structure). The crystal structure of one representative compound (an oligomer with three I atoms in the backbone and 5-phenyltetrazole end groups) was solved and refined from synchrotron powder X-ray diffraction. The novel compounds were characterized by cyclic voltammetry and were found to be strong oxidants. In addition, they proved to be useful reagents for the iodotetrazolylation of unsaturated compounds such as styrene and cyclohexene and for the transfer of tetrazole groups to N, N-dimethylaniline.

Functionalization of cis‐1,4‐polyisoprene using hypervalent iodine compounds with tetrazole ligands

“…The combined CH 2 Cl 2 layers were washed with distilled water (3 × 10 mL) and dried over anhydrous Na 2 SO 4 , and then the solvent was evaporated using a rotary evaporator to obtain a yellow oil as the crude product, which was dissolved in CH 2 Cl 2 (1.0 mL). To the solution, hexane (20.0 mL) was added and pure crystals of the product were obtained upon leaving the mixture undisturbed for approximately 1 h. The GC‐MS and 1 H NMR spectra of the product were identical to those described in the literature …”

“…Poly(ethylene oxide) monomethyl ether 4‐pentynoate (MePEO‐P, M n  2,000 g mol −1 ) was synthesized by esterification of the corresponding alcohol, MePEO‐OH, with 4‐pentynoic acid . The HV iodine(III) compounds with various tetrazole ligands (C 6 H 5 I(N 4 CR) 2 ( 1a‐c )) were synthesized from C 6 H 5 I(O 2 CCF 3 ) 2 and the potassium salts of 5‐substituted tetrazoles, according to a reported procedure …”

“…37 The HV iodine(III) compounds with various tetrazole ligands (C 6 H 5 I(N 4 CR) 2 (1a-c)) were synthesized from C 6 H 5 I(O 2 CCF 3 ) 2 and the potassium salts of 5-substituted tetrazoles, according to a reported procedure. 36…”

“…To the solution, hexane (20.0 mL) was added and pure crystals of the product were obtained upon leaving the mixture undisturbed for approximately 1 h. The GC-MS and 1 H NMR spectra of the product were identical to those described in the literature. 36 Reaction of polyIP with C 6 H 5 I(N 4 CR) 2 (R CH 3 , C 6 H 5 , 4-CH 3 C 6 H 4 ) in the Presence of I 2 In a 100 mL reaction flask, wrapped with aluminum foil (to protect the contents from light), a stir bar was placed, and C 6 H 5 I[N 4 C(4-CH 3 C 6 H 4 )] 2 (1c, 7.67 g, 14.7 mmol) and dry CH 2 Cl 2 (10.0 mL) were added. The flask was immersed in a water bath at 25 C, and the contents were stirred.…”

“…The organic compounds of polyvalent iodine, also named hypervalent (HV) iodine compounds, owing to the presence of 3‐center‐4‐electron bonds, have attained great importance in organic synthesis . We recently reported the synthesis of HV iodine(III) compounds containing various tetrazoles as the ligands and demonstrated their use in the iodo‐tetrazolylation of alkenes (cyclohexene and styrene) as well as their ability to transfer radically tetrazole groups to substrates such as N , N ‐dimethylaniline . In this article, the fast room temperature iodo‐tetrazolylation of polyIP is described along with further chemical transformations of the prepared functionalized products.…”