Florencio Moreno Jiménez

New procedures for the synthesis of heterocyclic substituted and 2,4-difunctionalized pyrimidines

Abstract N -Tosyl-2- and -3-acetylpyrrols 1 or N -tosyl-2-pyrrolidone 5 were condensed with cyano compounds in the presence of triflic anhydride (Tf 2 O) to yield heteroarylpyrimidines. 2,4-Difunctionalized pyrimidines were obtained by reaction of the corresponding 2,4-bis(methylsulfonyl)pyrimidines with nucleophiles.

ABOUT THE TIMING OF WAGNER-MEERWEIN AND NAMETKIN REARRANGEMENTS, 6,2-HYDRIDE SHIFT, PROTON ELIMINATION AND CATION TRAPPING IN 2-NORBORNYL CARBOCATIONS

The reaction of different substituted 2-norbornanones 1 with triflic anhydride in the presence of nitriles 6 is carried out in order to study the factors that influence on the different reaction possibilities of 2-norbornyl carbocations. The syntheses of interesting annulated pyrimidine derivatives 10 and conformationally rigid 1,3 disubstituted products are described.

Enantiospecific synthesis of substituted 1-norbornyl trifluoromethanethiosulfonates and 1-norbornanethiols

Abstract New homochiral 1-norbornylthiotriflates 6 and 7 and 1-norbornanethiols 8 and 9 are easily prepared starting from naturally occurring 2-norbornanones 1 . The key step is the reaction of chiral 2-norbornanethiones 2 with Tf 2 O under mild conditions.

Enantiospecific synthesis of substituted 1-norbornanesulfonic acids and 1-norbornanesulfenic and sulfonic acid derivatives

Abstract New homochiral 1-norbornanesulfenic and sulfonic acid derivatives 2 – 7 , as well as the sulfonic acids 8 , are easily synthesised starting from 2-methylene-1-norbornylthiotriflates 1 . This new class of homochiral bridgehead thiosulfonates was prepared by us from naturally occurring (+)-camphor and (−)-fenchone. Nucleophilic substitution at the sulfenyl sulfur atom is the key step for this synthetic strategy.

Electron ionization mass spectral studies of bridgehead-substituted norbornan-2-ones: camphor derivatives.

The electron ionization (EI) mass spectra of a series of bridgehead-substituted 3,3-dimethylnorbornan-2-ones, derived from natural (1R)-(+)-camphor, have been studied and their cleavage mechanisms rationalized on the basis of the substituent shifts as well as on the identification of relevant peaks through accurate mass measurements and collision-induced dissociation (CID) tandem mass spectrometric experiments. The fragmentation patterns are very dependent on both the structural nature and the electronic properties of the bridgehead substituent. The driving force for the main fragmentation pathways are competitive cleavages of the C(1)-C(2) and C(2)-C(3) bonds directed by the bridgehead substituent and either the gem-dimethyl or carbonyl groups. These cleavages lead to distonic ions in which the charge is preferentially located either at the C(1), C(2) or C(3) positions depending on the electronic character and structural nature of the bridgehead substituent. This charge distribution determines the subsequent rearrangements and fragmentations.

Cheap and long-life reusable polymer for asymmetric organozinc catalysis based on camphor-derived hydroxyamides.

Polystyrene grafted with a chiral zinc-complexing camphor-derived N,N-disubstituted hydroxyamide is proposed as a new type of functional polymer of high reusability for the development of sustainable organozinc-catalyzed asymmetric reactions. The main goal of this new functional polymer is the ease of the hydroxyamide-moiety preparation (cheap chiral ligand obtained straightforwardly from an enantiopure starting material coming from the chiral pool), as well as its chemical robustness when compared with other related zinc-complexing functional groups. The latter allows the polymer to be active after multiple applications, without significant loss of its catalytic activity. This fact is exemplified by the design and preparation of a polymer functionalized with a bis(hydroxyamide) proved previously as active in the homogeneous enantioselective addition of diethylzinc to aldehydes. The result is a cheap functional polymer with a very high reusability (the enantioselectivity and chemical yield are maintained practically constant after 20 applications). Additionally, a methodology for the multicycle use of these functional polymers is presented.

Electron ionisation mass spectral studies of bridgehead-fused Δ2-norbornanethiazolines

The electron ionisation (EI) mass spectra of a series of bridgehead-fused Delta2-norbornanethiazolines, a new class of bridgehead-norbornane derivatives, have been studied and their cleavage mechanisms rationalised on the basis of the substituent shifts as well as on the identification of relevant peaks through accurate mass measurements and collision-induced dissociation tandem mass spectrometric experiments. The fragmentation patterns of isomeric pairs of 6,6- and 10,10-dimethylnorbornanethiazolines are almost identical, probably due to an initial isomerisation of molecular ion previous to the fragmentation. In general, the dominant peaks in the spectra of all the studied compounds originate from initial alpha-cleavages of C(5)-C(6) or C(1)-C(10) bonds, followed by concomitant homolytic cleavage of C(1)-C(9) and C(7)-C(10) bonds. The driving force for this fragmentation pathway, directed by the gem-dimethyl group, is the formation of a highly stabilised thiazolilmethyl cation which constitutes the base peak in all the spectra and allows the identification of these interesting ligands.

A novel and simple procedure for the enantiospecific synthesis of bridgehead norbornane thioethers and thiocyanates

An easy three-step route for the enantiospecific synthesis of novel 1-norbornyl thioethers and thiocyanates from readily available natural fenchone and camphor is described. The key step of the synthetic route is the nucleophilic substitution over the sulfenyl sulfur atom of the intermediate thiotriflates by the corresponding C-nucleophiles.