On the relationship between the Hunsdiecker and Simonini reactions

Decarboxylative Halogenation of Organic Compounds

“…While the highest yields were obtained for the alkyl bromides, the chloride analogues usually had significantly lower yields due to the radical chlorination of both the starting acid and the product. 27 Alkyl iodides could be obtained in a similar manner, although the outcome of the reaction significantly depended on the reaction conditions. The reaction of silver carboxylates with I 2 was studied at the end of the 19th century as a method for the preparation of esters and is known as the Simonini reaction.…”

“…Bromodecarboxylation also produces esters as a side product, but in smaller amounts, while no esters were isolated for the chlorodecarboxylation process. 27 With respect to the scope, the Hunsdiecker reaction can be efficiently applied to primary and secondary aliphatic acids ( Scheme 5 ). Yields of the primary alkyl bromides vary in a range of 60–90%, while secondary carboxylic acids are less efficient (the yield is 30–70%).…”

“…Tertiary bromides are usually not formed in more than a trace amount since rapid decomposition in the presence of metal salts was observed. 27 Only the rigid caged systems deliver corresponding tertiary bromides in good to excellent yields (e.g., 110, 111–114 ). Unlike the reaction of silver salts, attempts to introduce iodine in the bridgehead position via this approach usually led to the formation of the Simonini ester as a sole product, and no alkyl iodide was observed.…”

O-Mesityl(sulfonyl)hydroxylamine: A Novel Reagent for Reduction of Electron Deficient α,β-Unsaturated Carbonyl Derivatives

“…Filtered the white solid and wash with hexane (100 mL), dry under vacuum gives the 28.3 g of phenyl hydrazone 6 in 95% yield. 1 H NMR (200 MHz, CDCl3): δ 7.25-7.33 (m, 2H), 6.88-7.00 (m. 3H), 2.45-2.65 (m, 2H), 2.08-2.16 (m, 3H), 1.85 (ddd,1H,J = 3.8,8.6,17.8 Hz), 1.39-141 (m, 1H), 1.29 (s, 3H), 0.97 (s, 3H). 13 C NMR (50 MHz, CDCl3): δ 172.…”

Chapter 3. Reaction mechanisms. Part (i) Pericyclic reactions

“…Pericyclic reactions are included in reviews of tandem reactions for organic synthesis3 and of new reactions for forming heterocycle^.^ A theoretical study (RHF/6-3 lG* and B-LYP/6-3 1G*) has been applied to secondary kinetic isotope effects in a range of pericyclic reactions. It calculates for [4 + 21 cycloadditions large differences for the 'in' and 'out' diene terminal hydrogens and smaller differences for the endo and exo dienophile hydrogens, for electrocyclic transition states large differences for the 'in' and 'out' hydrogens, and for [3,3] sigmatropic transition states differences for the axial and equatorial hydrogens. The effects are due to differences in bending force constants.…”