We report a metal-free procedure for transformation of phenols into esters and amides of benzoic acids via a new radical cascade. Diaryl thiocarbonates and thiocarbamates, available in a single high-yielding step from phenols, selectively add silyl radicals at the sulfur atom of the C═S moiety. This addition step, analogous to the first step of the Barton-McCombie reaction, produces a carbon radical which undergoes 1,2 O→C transposition through an O-neophyl rearrangement. The usually unfavorable equilibrium in the reversible rearrangement step is shifted forward via a highly exothermic C-S bond scission in the O-centered radical, which furnishes the final benzoic ester or benzamide product. The metal-free preparation of benzoic acid derivatives from phenols provides a potentially useful alternative to metal-catalyzed carbonylation of aryl triflates.

Radical merry‐go‐round: A highly efficient metal‐free transformation of phenols into benzamides is designed through one‐step conversion of phenols to aryl thiocarbamates and a subsequent radical addition/rearrangement/fragmentation cascade. Computational analysis fully rationalizes the experimentally observed selectivity. Despite the possible competition from NC fragmentation and N‐neophyl rearrangement, the transformation exclusively follows the most kinetically and thermodynamically favored O‐neophyl rearrangement path.

Relative risk and Odds ratios using standard procedure as well as the Cochran-Mantel-Haenszel test to account for confounding factors were calculated. A value of P<0.05 was considered significant.RESULTS: No differences were denoted in normal fertilization rates and in both the number of usable and expanded blastocysts obtained at day-6 of development between the two Groups [505 out of 736 (62.1%); 42 out of 505 (8.5%) and 25 out of 505 (5.2%)] vs.[501 out of 737(68.6%); 37 out of 501 (8.4%) and 33 out of 501(3.7%)] with p values of 0.8680, 0.8580 and 0.4333,respectively. Significantly improved rates for usable and expanded blastocysts were found for Group 1 at Day-5 of embryo development [216 out of 505 (46.4%) and 103 out of 505 (19.5%)] vs [196 out of 501 (35.6%) and 96 out of 501 (12.3%)] (P¼0.0109 and P¼0.0268, respectively). The rates of cumulative usable and total expanded blastocysts at Day-5 plus Day-6 of development was statistically higher in Group 1 compared to the Group 2 (p¼0.0081and p¼0.0191, respectively).CONCLUSIONS: The results the current study demonstrate for the first time that the adjustment of the ORP levels in the embryo culture medium to physiological ORP levels through antioxidant supplementation is beneficial for older patients undergoing IVF treatments as it provides significantly increased number of usable and expanded blastocysts rates compared to the conventional embryo culture system.IMPACT STATEMENT: The adjustment of supraphysiological ORP levels normally found in commercial culture media to a physiological state may facilitate significantly improved rates of usable and expanded blastocysts during the IVF treatment of women advanced maternal age, which may increase their chances of getting pregnant.

Radical O→C Transposition: A Metal-Free Process for Conversion of Phenols into Benzoates and Benzamides. -It provides a new and efficient method to prepare various aromatic carboxylic acid esters and amides. -(BAROUDI, A.; ALICEA, J.; FLACK, P.; KIRINCICH, J.; ALABUGIN*, I. V.; J. Org. Chem. 76 (2011) 6, 1521-1537, http://dx.