29736-80-9Relevant articles and documents
New insights into the reduction of β,δ-diketo-sulfoxides
Hanquet, Gilles,Salom-Roig, Xavier J.,Gressot-Kempf, Laurence,Lanners, Steve,Solladie, Guy
, p. 1291 - 1301 (2007/10/03)
New developments in the reduction of β,δ-diketo-sulfoxides, a reaction that affords important key intermediates for total synthesis, are described. We showed without ambiguity using NMR experiments, that the β-carbonyl group is totally enolised. This result is inconsistent with the previous hypothesis, which supposed the other tautomer (enolisation at the δ-position) as the major one. We propose a rationale to explain the side reactions occurring during the reduction of unprotected β,δ-diketo-sulfoxides and showed that judicious protection of the δ-carbonyl group gave all diastereoisomers of β-hydroxy-δ-ketosulfoxides.
Reactions of fused and unfused α-pyrones with magnesium alkoxide, sodium alkoxide and water as the nucleophile: effects of chelation
Crombie, Leslie,Games, David E.,James, Alun W. G.
, p. 2715 - 2724 (2007/10/03)
The reactions between a series of α-pyrones (two mono- and three fused) and the non-chelating base sodium alkoxide, the chelating base magnesium alkoxide and water as the nucleophile, have been studied.Aromatic and other products formed reflect the points of attack on the pyrone systems and when sodium methoxide is used the ensuing cyclisation is preferentially by aldol mechanisms.The employment of excess magnesium methoxide or ethoxide gives magnesium-chelated precursors and the nature of products now depends on these intermediates, and the protection afforded by such magnesium chelation to the reaction products.In the case of structures containing chelated β-keto ester features the chelates are screened from attack as aldol acceptors, but are effective Claisen acceptors.In such chelates an adjacent methylene is activated by further magnesium alkoxide to act as an aldol or Claisen donor.These contrasting aldol/Claisen reactivities, as between a non-chelating and a chelating base, are illustrated in the ensuing chemistry of the pyrones.Treatment with water releases the main carbon chain with decarboxylation, from which new products may form.
Chemistry of enol silyl ethers. A general synthesis of 3-hydroxyhomophthalates and a biomimetic synthesis of sclerin
Brownbridge, P.,Chan, T. H.,Brook, M. A.,Kang, G. J.
, p. 688 - 693 (2007/10/02)
A general synthesis of 3- hydroxyhomophthalates is developed and applied to the synthesis of sclerin (24), a compound possessing plant-growth activity; the critical step in the synthesis of 24 can be considered as the controlled condensation of a di-β-carbonyl unit with a tri-β-carbonyl unit.
