Nicole Maigrot

Synthesis and X‐ray Crystal Structures of Silacalix[n]phosphinines: The First sp2‐Based Phosphorus Macrocycles

Several unique examples of phosphorus macrocycles, with PC double bonds, are obtained by a simple synthetic sequence that exploits the reactivity of 1,3,2-diazaphosphinines with silyl-substituted 1,4-diynes. In addition to the synthesis of calix[3] 1 and calix[4] 2, mixed macrocycles incorporating phosphinine, furan or thiophene units have also been prepared and structurally characterized.

Synthesis and Reactivity Towards Cationic Group 11 Metal Centers of an Extended Silacalix-[3]-phosphinine Macrocycle

A synthetic route to a new type of phosphinine-based macrocycle has been developed. This approach involves the reaction of a phosphinine bearing two pendant SiMe2OSiMe2CCR (R = Ph) (5) groups with two equivalents of a diazaphosphinine (1). The 2,6-bis(azaphosphininedimethylsilyl)phosphinine (6) formed was then reacted under dilute conditions with a second equivalent of phosphinine 5 to produce the new macrocycle 4. The X-ray crystal structure of 4 reveals no particular strain, and the macrocycle was fluxional in solution even at low temperature (−60 °C). Reactions of macrocycle 4 with [Cu(MeCN)4][BF4], [Ag][BF4] and [AuCl(SMe2)] in the presence of GaCl3 as chloride abstractor yielded the corresponding cationic complexes 8, 9, and 10. The X-ray crystal structure of the copper complex 8 was recorded. As expected, the overall geometry around copper is trigonal planar. The macrocycle adopts a distorted arrangement to accommodate this geometry, and the phosphinines do not bind copper in a linear fashion. The examination of metric parameters suggests that the aromaticity of the rings has not been perturbed due to a weak bonding between phosphorus atoms and copper. (© Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002)

Another synthesis of 1,3-diphospholyl anions and their use for the preparation of 1,1′,3,3′-tetraphosphaferrocenes

Abstract A new series of 1,3-diphospholyl anions has been obtained from 1,3-diphenyl-1,3-diphosphol-4-enes via the metallation of the PCH2P unit by n-butyllithium followed by the cleavage of the two PPh bonds by lithium in THF. These anions have been allowed to react with the bis-η6-p-xylene)iron dication to prepare novel 1,1′,3,3′-tetraphosphaferrocenes which have been characterized by X-ray crystal structure analysis.

Unsaturated Four-Membered Phosphorus-Carbon Rings: From Organic to Coordination Chemistry

Abstract The chemistry of 1,2-dihydrophosphetes and 1,2-dihydro-1,2-diphosphetes is comprehensively reviewed. Several applications such as the synthesis of tetraphosphafulvalenes and 1,3-diphospholyl anions are mentioned. The interconversion with open-chain 1-phospha- and 1,4-diphosphadienes is emphasized. The various coordination modes are discussed.

Reductive cleavage of axially disymmetric tertiary amines and quaternary ammonium salts by lithium aluminium hydride. Synthesis of new 1,1′-binaphthyl substituted amines

Axially disymmetric tertiary amines or quaternary ammonium salts A are synthesized by double alkylation of primary or secondary amines with racemic or optically pure 2,2′-bis (bromomethyl)-1,1′-binaphthyl. Their reductive cleavage by lithium aluminium hydride in refluxing THF leads to chiral secondary or tertiary amines B, substituted by a binaphthyl unit, with high yields and absence of racemization.

Siloxa-bridged-cyclophanes featuring benzene, thiophene and pyridine units

Two octamethyldisiloxa-bridged [3.3]cyclophanes (1 and 2) and a dodecamethyltrissiloxa-bridged [3.3.3]-cage compound (3) were prepared by hydrolysis of the chlorosilyl monomers. This general route was also employed for the preparation of two octamethyldisiloxa-bridged [3.3]heterophanes featuring two thiophene (14) or pyridine (17) moities.

The 1,2-dihydro-1,2-diphosphete-1,4-diphosphadiene equilibrium. X-ray structures of [μ2,μ2,η1,η1-(Ph)8C4P4]W2(CO)6 and [μ1,μ1-(Ph)4C2P2]W2(CO)10

Abstract As its P2W2(CO)10 dicomplex, the ring of 1,2,3,4-tetraphenyl-1,2-dihydro-1,2-diphosphete undergoes a reversible conrotatory opening to give the corresponding 1,4-diphosphadiene dicomplex which can be trapped as [4+2] cycloadducts with N-phenylmaleimide, maleic anhydride, acrylonitrile and benzaldehyde. X-ray crystal structure analysis indicates a weakening of the PP bond of the 1,2-dihydro-1,2-diphosphete upon complexation: the PP bond length increases from 2.248(1) A in the free ring to 2.281(3) A in the complex explaining why this reversible opening takes place only in the complex.

Titanocene and zirconocene complexes of a phosphorus analog of an Arduengo's carbene: Application in the synthesis of 1,3-diphosphafulvenes

Titanocene and zirconocene carbene complexes of a phosphorus equivalent of an Arduengos carbene have been synthesized in the coordination sphere of titanocene and zirconocene and exhibit a nucleophilic character which has been exploited in the synthesis of 1,3-diphosphafulvenes.

2-Diphenylphosphino-1,3-diphospholide anions

The title compounds are easily obtained in four steps from 4,5-disubstituted 1,3-diphenyl-1,3-diphosphacyclopent-4-enes (1). Metallation of the PCH2P unit of 1 followed by reaction with Ph2PCl allows a diphenylphosphino group to be grafted onto 1 at the C2 carbon. After removal of the remaining C2H proton by a base, selective cleavage of the two P1Ph and P3Ph bonds by lithium in THF affords the corresponding 2-diphenylphosphino-1,3-diphospholide ions (5). In one case, the reaction of n-butyllithium with 1a leads to an opening of the five-membered ring via a nucleophilic attack at phosphorus. A bis-(phosphino)methanide ion (8) is thus obtained. Its chemistry has been investigated briefly.

High diastereoselectivity in the reaction of α-aminonitriles bearing an (S)-(+)-2-methoxymethylpyrrolidine group with Grignard reagents

(S)-(+)-2-Methoxymethylpyrrolidine induces high diastereoselectivities (80% diastereoisomeric excess) in the reaction of α-aminonitriles with Grignard reagents.