Lluís Pagès

Influence of functional substitution of allyl halides on their ni(co)4 promoted carbonylative cycloaddition with acetylenes

Abstract The effect of functional substitution of allyl halides on the outcome of the title reaction has been studied. Electron withdrawing and olefinic groups had different effects depending on their location. When they were placed at the central position of the allyl moiety carbonylative cycloaddition was found to be the main reaction, in acetone, to yield exclusively cyclohexenone (or aromatic) derivatives. In contrast, the same groups at the terminal site and in exteded conjugation with the allylic funtion were shown to favour competing side reactions such as allyl self-coupling. However, only cyclopentenones were obtained from either centrally or terminally substituted silylallyl halides. Substitution at both ends of the allyl moiety led to the formation of 4,5-disubstituted cyclopentenones. Important mechanistic information could be achieved from determination of the relative stereochemistry in these compounds.

Synthesis and structure–activity relationships of γ-carboline derivatives as potent and selective cysLT1 antagonists

A gamma-carboline series of cysLT(1) receptor antagonists has been prepared. Some of the compounds show good potencies both, in vitro and in vivo, compared to the standard compounds.

Synthetic applications of 2-aryl-4-piperidones. X Synthesis of 3-aminopiperidines, potential substance P antagonists

Abstract A general method is described for the synthesis of 3-aminopiperidines from 4-piperidones based on a KOEt treatment of the tosylate of the corresponding oximes (Neber rearrangement). The procedure is applied to the synthesis of N -benzyl-3-amino-4,4-diethoxypiperidine ( 13 ), ( R )- N -(2-hydroxy-1-phenyl)ethyl analogues 18 , and 2-phenyl derivatives 27–28 . The methoxybenzylation of the primary amino group of these aminopiperidines leads to a series of potential substance P antagonists.

Fused bicyclic systems through a ni-mediated intermolecular cyclopentenone annulation

Abstract The extension of the Ni(CO) 4 promoted carbonylative cycloaddition of acetylenes and allyl halides to the 5–8 membered 3-halocycloolefins leads efficiently to the formation of the corresponding 4–5 fused 2-cyclopentenones with high regio and stereoselectivities.

New practical synthesis of spirocyclopentenones

Abstract The reaction of 1-bromomethyl-1-cycloalkenes and acetylenes in the presence of tetracarbonylnickel affords moderate to good yields of spirocyclopentenones in a regio and stereoselective process.

Preference for β-H elimination in the termination of the Ni-promoted carbonylative cycloaddition of 2-haloethylidene-cycloalkanes and alkynes

Abstract The reaction of 2-haloethylidenecycloalkanes (ring size: 5, 6, 7, 8) with either methyl-2-butynoate or 2-butynyl methyl ether and Ni(CO) 4 in methanol affords mainly two type of bicyclic compounds: 5-cycloalkenylidenecyclopent-2-enones and 5-(1-cycloalkenyl)cyclopent-2-enones. The origin for the diversion of the process towards elimination instead of alkoxycarbonylation is interpreted as the result of the mutual conformation of the two rings in the intermediates favouring either elimination through enol formation or syn β -elimination. In this last case, the terminating step can proceed in two different modes, namely, intraannularly or interannularly. While for the acetylenic ester, the product from interannular elimination is exclusive or predominant regardless of the ring size of the starting halide, for the 2-butynyl methyl ether, the product distribution is found to strongly depend on the nature of the allyl component. Thus, in this case, intraannular elimination is exclusively found in the reaction of the cyclopentylidene halide, while products from interannular elimination are produced in the reaction of the eight-member homologue. Mixtures of the two types of compound are formed from the cyclic 6 and 7 allyl halides.