Solving the puzzling competition of the thermal C²–C⁶ vs Myers–Saito cyclization of enyne-carbodiimides

• Anup Rana,
• Mehmet Emin Cinar,
• Debabrata Samanta and
• Michael Schmittel

Beilstein J. Org. Chem. 2016, 12, 43–49, doi:10.3762/bjoc.12.6

• pathway if the trapping reaction by hydrogen transfer is no more rate determining. Keywords: DFT computation; diradical; enyne-carbodiimides; hydrogen transfer; thermal cyclization; Introduction The thermal cyclizations of enediynes [1][2][3][4][5][6], enediallenes [7][8][9][10], bisallenes [11], enyne

Interplay of ortho- with spiro-cyclisation during iminyl radical closures onto arenes and heteroarenes

• Roy T. McBurney and
• John C. Walton

Beilstein J. Org. Chem. 2013, 9, 1083–1092, doi:10.3762/bjoc.9.120

• resolved spectra only at 230–235 K (Figure 3). The corresponding benzofuranyl-iminyl was not detectable at 230 K or above. The EPR hfs obtained from simulation of the spectrum (Table 2) show this to be a benzyl type radical and we assign it structure 12a (Scheme 2). A DFT computation for 12a at the UB3LYP

• the tert-butyl substituent of the solvent. It is known that ArCMe=N• type radicals do not add to t-BuPh under EPR conditions [19][37] neither do EtO• radicals (from dissociation of 6), and hence, we assign this spectrum to the ethoxycarbonyloxyl adduct 9a. This identification was supported by a DFT

• computation [38] that gave hfs in close agreement with experiment (Table 1). This was a surprising result because previously the only radicals of type 9 that had been spectroscopically detected had resulted from additions of phenyl [34] or bridgehead radicals (bicyclo[2.2.2]oct-1-yl and adamantyl) [39]. These

EPR and pulsed ENDOR study of intermediates from reactions of aromatic azides with group 13 metal trichlorides

• Giorgio Bencivenni,
• Riccardo Cesari,
• Daniele Nanni,
• Hassane El Mkami and
• John C. Walton

Beilstein J. Org. Chem. 2010, 6, 713–725, doi:10.3762/bjoc.6.84

• +•, containing a single F-atom. The DFT computation on the dimer hfs gave satisfactory agreement (Table 1), with the possible exception of the para-F hfs. However, DFT-computed a(F) values varied from 7.2, to 7.1, to 9.5 and 4.3 G with 6-31G(d), 6-31+G(d,p), DGDZVP and 6-311++G(d,p) basis sets, respectively