A. B. Kostitsyn

Synthesis and spectral properties of cyclopropyl-substituted phosphaalkenes

Cyclopropanecarboxylic acid chlorides5a-d react with tris(trimethylsilyl)phosphane6 in benzene at −2 °C to form cyclopropylcarbonyl-bis(trimethylsilyl)phosphanes7. These products undergo silylic rearrangement at 25 °C to yield phosphaalkenes8. Compounds 8a,b,d are formed as mixtures ofZ- andE-isomers where the latter predominate. In the case of8c, theZ-isomer is formed exclusively.

Reaction of diazoalkanes with unsaturated compounds. 11. Relative reactivity of olefins on catalytic cyclopropanation with diazomethane and palladium catalysts

The relative reactivity of unsaturated compounds on catalytic cyclopropanation with diazomethane in the presence of catalysts based on Pd2+ [Pd(OAc)2, Pd(acac)2, (PPh3)2·PdCl2] has been studied using competing reactions. An interconnection was shown between the relative reactivity of the olefins and the coordinating activity of the C=C bond depending on its strain and spatial environment.

Reaction of diazoalkanes with unsaturated compounds. 9 Catalyzed cyclomethylenation of trimethylsilylacetylenes by diazomethane

The catalyzed reaction of methyl-, propyl-, and cyclopropyltrimethylsilylacetylenes with diazomethane in the presence of CuCl leads to the corresponding cyclopropenes and bicyclobutanes with overall yields of up to 70%, and also to the products of incorporation of a methylene group into the C3-H bond of the cyclopropenes formed (2–9%). Partial catalyzed isomerization of the 1-trimethylsilyl-2-cyclopropylcyclopropene formed from trimethylsilylcyclopropylacetylene, into 1-trimethylsilyl-1-cyclopropylallene (yield ∼50%) was discovered to proceed under the reaction conditions.

Reactions of diazoalkanes with unsaturated compounds 7. Catalytic cyclopropanation of 1-alkoxy-, 1-acetoxy-, and 1-(trimethylsilyloxy)buta-1,3-dienes with diazomethane

Cyclopropanation of 1-butadienyl ethers or esters with diazomethane proceeds selectively in the presence of (PhCN)2PdCl2, as opposed to CuCl, at the less polar terminal double bond in these dienes when the molar proportions of reactants and catalyst are 1 ∶ (1.3−2) ∶ (0.002−0.005) to give the 2-cyclopropylvinyl ethers or esters in yields of 80–85%.

Catalytic cyclopropanation of oxygen- and nitrogen-containing allyl derivatives using diazomethane

Cyclopropanation using diazomethane has mostly been studied in the case of unsaturated hydrocarbons and is carried out with high selectivity [i, 2]. On the other hand, the reaction of CH2N2 with olefins containing functional substituents proceeds less selectively and, in addition to cyclopropanation, is complicated by side reactions related mainly to the formal insertion of a methylene fragment into the carbon--heteroatom or hydrogen--heteroatom bonds [3, 4]. Furthermore, the cyclopropanation of the simplest oxygenand nitrogen-containing allyl derivatives which hold greatest interest relative to organic synthesis has virtually not been studied.

The first quantitative preparation of bis(trimethylsilyl)acylphosphane by action of acyl halide on tris(trimethylsilyl)phosphane

Previously, we showed that the reaction between various cyclobutane- and cyclopropanecarboxylic acid chlorides and tris(trimethylsilyl)phospane, leading to phosphoalkanes with small cycles, proceeds via the corresponding intermediate cyclobutyl- and cyclopropylcarbonyl-bis(trimethylsilyl)phosphanes. The presence of the latter in the reaction mixture can be revealed by NMR methods at temperatures ranging from -3 to ~20 ~ However, due to their low thermostability, even in such conditions they exists as mixtures with the starting reagents and the corresponding phosphaalkenes. Thus, to date no acyl-bis(trimethylsilyl)phosphane is known to have been isolated or identified in the individual state. In the present work we describe the first example of preparation of a solution of acyl-bis(trimethylsilyl)phosphane in the pure state, by interaction between tris(trimethylsilyl)phosphane (2) and 1-bromocyclopropane carboxylic acid chloride. Thus, the addition of an equimolar amount of acyl chloride (1) in benzene or toluene to the phosphane (2) at temperatures below -2 ~ under argon leads to the formation of the only ( 1 -bromo- l -cyclopropylcarb onyl)-bis- (trimethylsilyl)phosphane (3) in quantitative yields (according to the data of 1H, 13C,and 31p NMR). The solution contains neither the starting reagents, nor the corresponding phosphaalkene even in minor amounts.

The formation of tetracyclo[7.2.1.02,5.02,8]dodeca-6,10-dienes under conditions of thermal isomerization of spiro[2.4]hepta-4,6-diene into bicyclo[3.2.0]hepta-1,3-diene

The formation of the novel hydrocarbons, tetracyclo[7.2.1.02,5.02,8]dodecadienes, as a result of thermal isomerization of spiro[2.4]hepta-4,6-diene into bicyclo[3.2.0]hepta-1,3-diene and its capture by 1,3-dienes is demonstrated. The conditions of thermal isomerization and dimerization of the spiroheptadiene are studied. Cyclopropanation of the polycyclic dienes formed by diazomethane in the presence of Pd-catalysts was accomplished, and occured solely through the norbornene double bond.

Reactions of diazoalkanes with unsaturated compounds 8. Catalytic cyclopropanation of allyl alcohols and allylamines with diazomethane

Allyl alcohols and allylamines have been cyclopropanated directly with diazomethane in the presence of palladium compounds to give 60–88% of cyclopropylmethanols and cyclopropylmethylamines, respectively, almost free from the products of formal insertion of methylene into the heteroatom-hydrogen bond.