Directed aromatic functionalization in natural-product synthesis: Fredericamycin A, nothapodytine B, and topopyrones B and D

• Charles Dylan Turner and
• Marco A. Ciufolini

Beilstein J. Org. Chem. 2011, 7, 1475–1485, doi:10.3762/bjoc.7.171

• . This was due in part to undesired base-promoted reactions of the enolizable ketone segments, but also to the slow rate of interconversion of 47 and 48 (only the former can produce the desired pyridone). Experiment revealed that it was best to carry out the Michael step with DBU in pyridine, followed by

Development of the titanium–TADDOLate-catalyzed asymmetric fluorination of β-ketoesters

• Lukas Hintermann,
• Mauro Perseghini and
• Antonio Togni

Beilstein J. Org. Chem. 2011, 7, 1421–1435, doi:10.3762/bjoc.7.166

• presence of Lewis acids As a starting point for our investigation, we chose to study the fluorinations of the readily enolizable β-ketoesters 1 and 2 and of α-cyanoester 3 as model compounds with the reagent F–TEDA under either “neutral” conditions [66][67][68][69][70][71] or in the presence of Lewis acids

Amines as key building blocks in Pd-assisted multicomponent processes

• Didier Bouyssi,
• Nuno Monteiro and
• Geneviève Balme

Beilstein J. Org. Chem. 2011, 7, 1387–1406, doi:10.3762/bjoc.7.163

• , thioether and ester groups, although enolizable alkylimines were not suitable under these conditions (Scheme 1). Replacement of the acid chloride with a chloroformate under 1 atmosphere of carbon monoxide as a fourth component led to ketocarbamates 3 in a single operation through a carbonylative coupling [3

• precatalysts and ligands, the palladacycle 10 in combination with the di-tert-butyl-2-biphenylphosphine (11) furnished the best results in terms of reaction time and yield. A large variety of imines and acid chlorides can be used in this reaction, with only enolizable imines and those bearing bulky nitrogen

Gold(I)-catalyzed synthesis of γ-vinylbutyrolactones by intramolecular oxaallylic alkylation with alcohols

• Michel Chiarucci,
• Mirko Locritani,
• Gianpiero Cera and
• Marco Bandini

Beilstein J. Org. Chem. 2011, 7, 1198–1204, doi:10.3762/bjoc.7.139

• outset of our investigation, we focused our attention on the non-enolizable allyl alcohol (Z)-1a, as a model candidate for the intramolecular oxaallyl alkylation. Our choice was dictated by the well-known reluctance of disubstituted malonyl derivatives to provide vinylbutyrolactones. This aspect was

• allylic SN1 mechanism is involved in the present methodology, due to the similar optical outcomes obtained in the presence of BA metal-free catalysts (entry 15, Table 1). Then, enolizable substrates carrying different malonyl residues (1b–e) were taken into account. In all cases the cyclization occurred

• intermediates) [53][54][55] in the nucleophilic attack was excluded; non-enolizable compounds being suitable candidates for the cyclization reaction. Conclusions In conclusion, we have documented an unprecedented example of gold-catalyzed lactonization with primary allylic alcohols. Cationic NHCAu carbene gold