Prenylflavonoids and prenyl/alkyl-phloroacetophenones: synthesis and antitumour biological evaluation.

Several prenylflavonoids have been synthesised and tested against human tumour cell lines. The prenyl unit has been geranyl or a labdane diterpene. These labdane-flavonoids have been synthesised for the first time.

Yamaguchi-type lactonization as a key step in the synthesis of marine metabolites: (+)-luffalactone.

A Yamaguchi-type cyclization of 5 and subsequent photochemical oxidation of the furanic ring are the key steps in the first synthesis of the marine metabolite (+)-luffalactone 4 and its epimer at C-16, 16-epi-luffalactone, 27. With this work, we have successfully established the absolute configuration of the natural product. The key intermediate 5 was obtained from the easily accessible diacetate 6a/6b.

Synthesis of an ent-halimanolide from ent-halimic acid.

An efficient synthesis of ent-halimanolide 2 (15,16-epoxy-12-oxo-ent-halima- 5(10),13(16),14-trien-18,2beta-olide), from ent-halimic acid has been achieved, corroborating the structure of the natural compound and establishing its absolute configuration.

Diastereoselective synthesis of delta-aminoacids through domino Ireland-Claisen rearrangement and Michael addition.

A novel domino reaction--stereoselective Ireland-Claisen rearrangement and asymmetric Michael addition--is described. A protocol starting from Baylis-Hillman adducts 3a-f using chiral lithium amide affords optically active gamma-substituted delta-amino acids 4a-f with high diastereoselectivities and enantioselectivities. The acid can be isolated easily from large-scale reactions and transformed to 2,3-disubstituted piperidines 11 or 2-substituted nipecotic acid derivates 12.

A novel strategy towards the asymmetric synthesis of orthogonally funtionalised 2-N-benzyl-N-alpha-methylbenzylamino- 5-carboxymethyl-cyclopentane-1-carboxylic acid.

The asymmetric synthesis of the orthogonally funtionalised compounds tert-butyl 2-N-benzyl-N-alpha-methylbenzylamino-5-methoxycarbonylmethylcyclopentane- 1-carboxylate and methyl 2-N-benzyl-N-alpha-methylbenzylamino-5-carboxymethylcyclo- pentane-1-carboxylate by a domino reaction of tert-butyl methyl (E,E)-octa-2,6- diendioate with lithium N-alpha-methylbenzyl-N-benzylamide initiated by a Michael addition, subsequent 5-exo-trig intramolecular cyclisation and posterior selective hydrolysis with trifluoroacetic acid is reported.