1,3-Sigmatropic Shifts in Carbonylketenes, Carbonyl Isocyanates and Analogous Compounds

✍ Scribed by Minh Tho Nguyen; Luc Landuyt; Hue Minh Thi Nguyen

• Publisher: John Wiley and Sons
• Year: 1999
• Tongue: English
• Weight: 124 KB
• Volume: 1999
• Category: Article
• ISSN: 1434-193X
• DOI: 10.1002/(sici)1099-0690(199902)1999:2<401::aid-ejoc401>3.0.co;2-u

✦ Synopsis

Antarafacial 1,3-sigmatropic shifts in carbonyl derivatives of PH 2 Ͼ F Ͼ OCH 3 Ͼ OH Ͼ SiH 3 Ͼ H Ͼ C 6 H 5 Ͼ CH 3 . The barrier heights range from 10 kcal/mol for Cl migration to 35 ketenes, isocyanates, thioketenes and thioisocyanates have been studied by means of ab initio MO calculations. Energy kcal/mol for phenyl migration. Several factors influencing the energy barriers including the existence of an n-electron barriers in 20 different systems have been uniformly determined at the MP4SDTQ/6-31G(d,p) level, based on

pair at the migrating atom, its size, electronegativity and ability to adapt to a hypervalent state, as well as the MP2/6-31G(d,p) geometries and corrected for zero-point energies. For formylketene, higher-level calculations using strengths of the breaking and forming bonds have been examined in detail. Generally speaking, 1,3-sigmatropic the QCISD(T) method and larger basis sets [up to 6-311++G(2df,2p)] have also been carried out. In rearrangements are feasible thermal unimolecular reactions even under mild experimental conditions. carbonylketenes, the migratory aptitude of the substituents R is established as follows: Cl Ͼ SH Ͼ NF 2 Ͼ NH 2 Ͼ BH 2 Ͼ markable feature of reported results is perhaps the detection