No abstract

The dearomatisation of aryldialkylphosphane–boranes and aryldialkylphosphane oxides under Birch reduction conditions, followed by treatment with reactive alkyl halides, provides the corresponding α‐functionalised (cyclohexa‐1,4‐dien‐3‐yl)phosphane derivatives. This reaction offers a method of choice for the synthesis of bulky (cyclohexadienyl)phosphanes.

Base-induced reaction between (1,4-cyclohexadien-3-yl)phosphine oxides and secondary phosphine oxides gives 3,4-bis(phosphinoyl)cyclohexenes and 2,3-bis(phosphinoyl)cyclohexenes through an in situ isomerization of one of the cyclohexadienyl double bonds and a subsequent Michael-type addition of the secondary phosphine oxide.

Michael addition of phosphorus nucleophiles to the unsymmetrically substituted tert-butyl(1,4-cyclohexadien-3-yl)phosphine oxide and its derivatives has been described. The addition proceeds with the formation of the mixture of two isomeric products with good yield and diastereoselectivity. The reaction of tert-butyl(cyclohexen-1-yl)methylphosphine oxide with phosphorus nucleophiles is base sensitive and might afford two epimers which differ at one chirality center. The absolute configuration of the products has been assigned on the basis of conformational and (1)H NMR analysis, and the mechanism of the reaction has been discussed. The Michael addition of phosphorus nucleophiles is postulated to proceed with or without consecutive epimerization of two α-carbanions.

Sodium in Liquid Ammonia -A Versatile Tool in Modifications of Arylphosphine Oxides. -The reaction of tertiary arylphosphine oxides with sodium in liquid ammonia is strongly influenced by the substrate structure. Thus, (aryl)dialkylphosphine oxides (I) undergo Birch reduction while diaryl(alkyl)phosphine oxides and triarylphosphine oxides provide access towards secondary phosphine oxides (IV). Cyclic phosphine oxides such as (IX) and (XI) undergo Birch reduction. However, an additional reduction of the phosphol-2-ene ring is observed [cf. (XIII)]. -(STANKEVIC*, M.; WLODARCZYK, A.; JAKLINSKA, M.; PARCHETA, R.; PIETRUSIEWICZ, K. M.; Tetrahedron 67 (2011) 45, 8671-8678, http://dx.doi.org/10.1016/j.tet.2011.09.045 ; Dep. Org. Chem., Maria Curie-Sklodowska Univ., PL-20-614 Lublin, Pol.; Eng.) -Mischke 11-170