Reaction of allene esters with Selectfluor/TMSX (X = I, Br, Cl) and Selectfluor/NH₄SCN: Competing oxidative/electrophilic dihalogenation and nucleophilic/conjugate addition

• A. Srinivas Reddy and
• Kenneth K. Laali

Beilstein J. Org. Chem. 2015, 11, 1641–1648, doi:10.3762/bjoc.11.180

• additions in halofunctionalization with TMSX/Selectfluor and thiocyanation reactions with NH4SCN/Selectfluor. These competing pathways are influenced by the nature of the anion, allene structure, and the choice of solvent. Keywords: allene esters; oxidative electrophilic dihalogenation/conjugate addition

• order to examine a possible influence of the structure of the allenoate on the product distribution, allene esters 2–6 were synthesized (Figure 1). The reactions of ethyl allenoate (2) with TMSBr, TMSI and with NH4SCN were studied in the presence of Selectfluor in MeCN and DMF (Scheme 5). With TMSBr and

• , especially in reactions with TMSI/Selectfluor (see Scheme 10), appears consistent with stabilization of the incipient allenyl cation in the oxidative/electrophilic pathway. Allene esters synthesized for this study. Reaction of benzyl allenoate (1) with TMSBr with and without Selectfluor (E/Z designations, as

Triazole–Au(I) complex as chemoselective catalyst in promoting propargyl ester rearrangements

• Dawei Wang,
• Yanwei Zhang,
• Rong Cai and
• Xiaodong Shi

Beilstein J. Org. Chem. 2011, 7, 1014–1020, doi:10.3762/bjoc.7.115

• . Many strategies have been developed to make the Au(I)-activated allene esters react with other proper substrates, forming interesting new products in a cascade fashion. The indene synthesis (Scheme 2b), reported by Nolan and coworkers, is one good example highlighting the importance of the cascade