Luis Castedo

Palladium-catalysed coupling of vinyl triflates with enynes and its application to the synthesis of 1α-25-dihydroxyvitamin D3

Abstract We describe a general approach, based on the palladium-catalysed coupling of enynes with vinyl triflates, for the construction of dienynes related to vitamin D metabolites and analogues. As an application of this method, an efficient convergent synthesis of 1α,25-dihydroxyvitamin D 3 starting from the Inhoffen-Lythgoe diol ( 6a ) and natural carvones has been carried out (11 steps, 28% overall yield from 6a ). This strategy allows labelling of the side chain in the final steps of the synthesis

Folding Control in Cyclic Peptides through N‐Methylation Pattern Selection: Formation of Antiparallel β‐Sheet Dimers, Double Reverse Turns and Supramolecular Helices by 3α,γ Cyclic Peptides

Peptide foldamers constitute a growing class of nanomaterials with potential applications in a wide variety of chemical, medical and technological fields. Here we describe the preparation and structural characteristics of a new class of cyclic peptide foldamers (3alpha,gamma-CPs) that, depending on their backbone N-methylation patterns and the medium, can either remain as flat rings that dimerize through arrays of hydrogen bonds of antiparallel beta-sheet type, or can fold into twisted double reverse turns that, in the case of double gamma-turns, associate in nonpolar solvents to form helical supramolecular structures. A 3alpha,gamma-CP consists of a number of multiples of a repeat unit made up of four amino acid residues of alternating chirality: three corresponding to alpha-amino acids and one to a gamma-amino acid (a cis-3-aminocycloalkanecarboxylic acid).

Synthesis of isoindoloisoquinoline alkaloids. A revision of the structure of (±)-nuevamine

Abstract An easy and efficient method for the synthesis of isoindoloisoquinolines, and the assignment of a new structure for the alkaloid (±)-nuevamine are reported.

Synthesis of phenethylenamides and their radical cyclization to 3-benzazepines

Abstract Synthetic approaches to enamides, intermediates of use in the synthesis of natural products, were studied as well as their 7-endo-trig radical cyclization to 3-benzazepines.

A new route to 3-(2-vinylphenyl)-2-methyl-2H-isoquinolin-1-ones and benzo(c)phenanthridines: total synthesis of fagaronine

Abstract Treatment of N -carbethoxy-1-benzylideneisoquinolines with LDA gives N -ethoxycarbonyl-1-amino-1-(2-vinylphenyl)-2-phenylethylenes, which can be transformed into 3-(2-vinylphenyl)-2-methyl-2 H -isoquinolin-1-ones by Bischler–Napieralski reactions, and thence into benzo[ c ]phenanthridin-6-ones. The use of this route for a new total synthesis of fagaronine is described.

Generation of cyclohexyne and its Diels-Alder reaction with α-pyrones

Abstract Cyclohexyne, which was generated from 2-(trimethylsilyl)cyclohexenyltriflate by fluoride-promoted β-elimination, reacts with α-pyrones to afford the corresponding tetrahydronaphthalenes.

Intramolecular aryne cycloaddition approach to aristolactams

Abstract A new procedure for the total synthesis of aristolactams, based on the intramolecular Diels-Alder reaction between styrene and aryne, is described.

Synthesis of isoquinoline alkaloids through a 10-membered lactam obtained by radical macrocyclisation

Abstract A new versatile method for the synthesis of isoquinoline alkaloids 3 and 5 is based on transannular cyclisation of a key macrocycle 2b obtained by an intramolecular addition of an aryl radical to a trimethylsilylacetylene.

The reaction of 1-alkyldihydroisoquinolines with benzyne. An unexpected entry to dibenzindolizines

Abstract The reaction of 1-ethylidene-2-formyl-1,2,3,4-tetrahydroisoquinolines 4a and 4b , or 1-ethyl-3,4-dihydroisoquinolines 3a and 3b , with benzyne led, by a formal 3+2 cycloaddition, to dibenzindolizines 5a and 5b , respectively. Compound 5b was also synthesized by photocyclization of enamine 6 .

The intermolecular benzyne cycloaddition approach to dehydronoraporprines and oxoaporphines. Total synthesis of PO-3

Abstract The synthesis of dehydronoraporphines and oxoaporphines has been achieved by means of the convergent and highly regioselective intermolecular benzyne cycloaddition approach. The first total synthesis of the quaternary oxoaporphine PO-3 is described.