Radical zinc-atom-transfer-based carbozincation of haloalkynes with dialkylzincs

• Fabrice Chemla,
• Florian Dulong,
• Franck Ferreira and
• Alejandro Pérez-Luna

Beilstein J. Org. Chem. 2013, 9, 236–245, doi:10.3762/bjoc.9.28

• in synthesis. Pivotal to the processes disclosed so far using alkylzinc derivatives is zinc atom radical transfer [4]. In general terms, the reaction involves a radical chain process initiated by the formation of an alkyl radical from the organozinc derivative in the presence of oxygen [5][6][7][8][9

• ][10][11][12][13][14]. The newly formed radical then undergoes one or more radical transformations before being reduced by the alkylzinc reagent through homolytic substitution at zinc, producing a new organozinc derivative along with an alkyl radical that sustains a radical chain. Overall, the in situ

Photoreactions of cyclic sulfite esters: Evidence for diradical intermediates

• Rick C. White,
• Benny E. Arney Jr. and
• Heiko Ihmels

Beilstein J. Org. Chem. 2012, 8, 1208–1212, doi:10.3762/bjoc.8.134

• decarbonylation results in an alkyl radical. The latter reaction yields bibenzyl (4) and toluene (7) in the photoreaction of 8. It should be noted that the diradical BR2 may be formed also upon photoinduced ring-opening reaction of an intermediate oxirane 2a, which is not detectable in the reaction mixture

Convergent syntheses of Le^X analogues

• An Wang,
• Jenifer Hendel and
• France-Isabelle Auzanneau

Beilstein J. Org. Chem. 2010, 6, No. 17, doi:10.3762/bjoc.6.17

• the carbon sulfur bond giving a thioacetate salt and an alkyl radical. The alkyl radical is then converted to the corresponding anion by a second electron transfer and the resulting anion is protonated by ammonia giving trisaccharide 1. In contrast to the thioacetate 31, treatment of the 6

Reduction of arenediazonium salts by tetrakis(dimethylamino)ethylene (TDAE): Efficient formation of products derived from aryl radicals

• Mohan Mahesh,
• John A. Murphy,
• Franck LeStrat and
• Hans Peter Wessel

Beilstein J. Org. Chem. 2009, 5, No. 1, doi:10.3762/bjoc.5.1

• studies on similar substrates by TTF [5][8][16][17] and TMTTF [16] had shown competitive trapping of the intermediate alkyl radical 46 by TTF+• or TMTTF+•. Preparation of indoles Following the successful implementation of the methodology on the synthesis of indolines, we next sought to harness the aryl

• )]. We expected that the aryl radical 53a generated by the reduction of arenediazonium salt 49a by TDAE would undergo 5-exo-trig radical cyclization onto the vinyl bromide to afford the alkyl radical intermediate 54a, from which Br• would be eliminated to afford the exocyclic alkene 50a (Scheme 6). Such

Part 2. Mechanistic aspects of the reduction of S-alkyl- thionocarbonates in the presence of triethylborane and air

• Florent Allais,
• Jean Boivin and
• Van Tai Nguyen

Beilstein J. Org. Chem. 2007, 3, No. 46, doi:10.1186/1860-5397-3-46

• , Newcomb,[14] following Wood's and Renaud's reports, carried out kinetic estimations of the rate of hydrogen abstraction by an alkyl radical from the complex between Et3B and water using the routine radical clock method. This author also came to the conclusion that hydrogen abstraction from the α position

Do α-acyloxy and α-alkoxycarbonyloxy radicals fragment to form acyl and alkoxycarbonyl radicals?

• Dennis P. Curran and
• Tiffany R. Turner

Beilstein J. Org. Chem. 2006, 2, No. 10, doi:10.1186/1860-5397-2-10

• setting is illustrated in Figure 4. Abstraction of iodine from 11 produces alkyl radical 12, which will rapidly cyclize to give key intermediate α-acyloxy radical 13a or α-alkoxycarbonyloxy radical 13b. Partitioning of 13a,b between bimolecular reduction to give 14a,b and unimolecular fragmentation to