Premium
Multiple Pentafluorophenylation of 2,2,3,3,5,6,6‐Heptafluoro‐3,6‐dihydro‐2 H ‐1,4‐oxazine with an Organosilicon Reagent: NMR and DFT Structural Analysis of Oligo(perfluoroaryl) Compounds
Author(s) -
Nishida Masakazu,
Fukaya Haruhiko,
Hayakawa Yoshio,
Ono Taizo,
Fujii Kotaro,
Uekusa Hidehiro
Publication year - 2006
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/hlca.200690239
Subject(s) - chemistry , organosilicon , reagent , substituent , carbon 13 nmr , fluorine 19 nmr , chemical shift , computational chemistry , stoichiometry , organic chemistry , nuclear magnetic resonance spectroscopy
The reagent Me 3 Si(C 6 F 5 ) was used for the preparation of a series of perfluorinated, pentafluorophenyl‐substituted 3,6‐dihydro‐2 H ‐1,4‐oxazines ( 2 – 8 ), which, otherwise, would be very difficult to synthesize. Multiple pentafluorophenylation occurred not only on the heterocyclic ring of the starting compound 1 ( Scheme ), but also in para position of the introduced C 6 F 5 substituent(s) leading to compounds with one to three nonafluorobiphenyl (C 12 F 9 ) substituents. While the tris(pentafluorophenyl)‐substituted compound 3 could be isolated as the sole product by stoichiometric control of the reagent, the higher‐substituted compounds 5 – 8 could only be obtained as mixtures. The structures of the oligo(perfluoroaryl) compounds were confirmed by 19 F‐ and 13 C‐NMR, MS, and/or X‐ray crystallography. DFT simulations of the 19 F‐ and 13 C‐NMR chemical shifts were performed at the B3LYP‐GIAO/6‐31++G(d,p) level for geometries optimized by the B3LYP/6‐31G(d) level, a technique that proved to be very useful to accomplish full NMR assignment of these complex products.