A versatile and metal-free approach for the synthesis of molecules bearing seven- and eight-membered rings is described. The strategy is based on the ring expansion of 1-vinylcycloalkanols (or the corresponding silyl or methyl ether) mediated by the hypervalent iodine reagent HTIB (PhI(OH)OTs). The reaction condition can be easily adjusted to give seven-membered rings bearing different functional groups. A route to medium-ring lactones was also developed.

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Tetrahydrofuran derivatives can be obtained by cyclofunctionalization of homoallylic alcohols bearing a terminal double bound by using [hydroxy(tosyloxy)iodo]benzene (HTIB, Koser's reagent) in the presence of a catalytic amount of I(2) (20 mol %) in MeOH under mild conditions. This transformation is an overall 5-endo-trig cyclization, which occurs by two different pathways. The first is a 4-exo-trig cyclization followed by ring expansion, whereas the second is an electrophilic addition followed by a 5-endo-tet cyclization.

A cultura do feijão apresenta grande importância econômica e social no Brasil e estudos sobre a função dos bioestimulantes associados a diferentes adubações nessa cultura ainda são incipientes. Desse modo, objetivou-se com este trabalho avaliar a influência do uso de bioestimulantes e suas interações com as adubações de NPK e micronutrientes no índice SPAD, índice de área foliar e a massa de matéria seca do feijoeiro da cultivar de feijão Pérola no município de Vitória da Conquista - BA. O trabalho foi desenvolvido na Universidade Estadual do Sudoeste da Bahia e teve o delineamento experimental em blocos casualizados arranjados em três fatores 2x2x4 sendo dois níveis de NPK (ausência e presença), dois níveis de micronutrientes (ausência e presença) e os bioestimulantes (ausência, Stimulate, Booster e Biozyme TF). Houve reposta significativa entre a interação dos bioestimulantes e NPK para o índice de área foliar e massa seca da parte aérea, com destaque para os bioestimulantes Booster e Biozyme TF que na ausência do NPK aumentaram o índice de área foliar. O NPK incrementou a massa seca da haste e o índice SPAD do feijoeiro.

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Recebido em 24/1/12; aceito em 23/4/12; publicado na web em 27/7/12 STUDY BY MASS SPECTROMETRY OF SOLUTIONS OF [HYDROXY(TOSYLOXY)IODO]BENZENE: PROPOSED DISPROPORTIONATION MECHANISMS. Solutions of [hydroxy(tosyloxy)iodo]benzene (HTIB or Koser´s reagent) in acetonitrile were analyzed using high resolution electrospray ionization mass spectrometry (ESI-MS) and electrospray ionization tandem mass spectrometry (ESI-MS/MS) under different conditions. Several species were characterized in these analyses. Based on these data, mechanisms were proposed for the disproportionation of the iodine(III) compounds in iodine(V) and iodine(I) species.

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