The Construction of Molecular Complexity from Functionalized Alkylidenecyclopropanes (FACPs)

As a special family of cyclopropanes, alkylidenecyclopropanes (ACPs), exhibit outstanding physical and chemical activities, which provide opportunities to participate in fascinating chemical transformations to access cyclopropane-containing units without ring-opening processes and other unavailable compounds through conventional routes with ring-opening processes owing to their strain-driven reactivity and synthetic accessibility. Nowadays, intramolecular reactions of methylenecyclopropanes (MCPs) or ACPs with adjacent functionalities have emerged as a powerful synthetic protocol for the construction of a variety of polycyclic and heterocyclic compounds with different sized skeletons through catalytic methods. Recently, we put forward the concept of functional alkylidenecyclopropanes (FACPs) and in this Minireview, we will summarize the reactions of FACPs after 2016 including several important early works from three aspects: 1) reactions with distal C−C bond cleavage, 2) reactions with proximal C−C bond cleavage (including ring-expansion reactions), and 3) reactions without C−C bond cleavage.     

O3/Pb(OAc)4: a new and efficient system for the oxidative cleavage of allyl alcohols

Allyl alcohols undergo oxidative cleavage, affording the corresponding carbonyl compounds in good yields, when treated with ozone-lead(IV) acetate under mild conditions.     

A novel C?C bond cleavage reaction of 2, 2′‐pyridil in solution

2,2′‐Pyridil reacted with CuCl₂ to give C–‐C bond cleavage product (picolinate)₂Cu, and its structure has been unambiguously confirmed by an X‐ray structural analysis.     

Si-C-Bond cleavage in 1-organylsilatranes by bromine or iodine chloride

The Si-C bond in I-organylsilatranes is cleaved by bromine or iodine chloride to yield 1-bromo- or 1-chlorosilatrane respectively. In the presence of Et2O or THF and under the action of dioxane dibromide, I-halosilatraneTranslated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 2075–2077, August, 1996.     

Cleavage of an aromatic carbon-heteroatom bond in a single step or successive steps?--A mechanistic distinction in the reduction of 5-bromo-1,3-dichloro-2-iodobenzene

The electrochemical reductive cleavage of the carbon-iodine bond in 5-bromo-1,3-dichloro-2-iodobenzene has been analyzed from the mechanistic point of view employing the Marcus theory of heterogeneous outer sphere electron transfer. The variation of the electrochemical transfer coefficient with potential has been estimated from the cyclic and convolution voltammetric studies. The comparison of the experimental reorganization energy with the theoretical predictions has revealed the existence of the radical anion of 5-bromo-1,3-dichloro-2-iodobenzene as a transient species.     

Thermal decomposition and isomerization of 2,2'-di(benzoxazolyl) disulfide

Heating 2,2′-di(benzoxazolyl) disulfide at 140–150 °C results in its decomposition with the elimination of elemental sulfur to yield 2,2′-di(benzoxazolyl) sulfide and 3-(2-benzoxazolyl)benzoxazoline-2-thione. Plausible reaction mechanisms are discussed. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1829–1831, October, 1993.     

立方体劈裂抗拉强度的复变函数解

立方体劈裂试验是测定砼抗拉强度的间接方法,本采用平面弹性得籴方法对试验中的劈拉应力进行了求解,对求解中出现的应力异常现象进行了分析处理,最终得到了可靠的解析解,试验证明,带状加载时,破坏从中心开始,由格里菲斯准则给出了砼的抗拉强度公式。     

Towards an Understanding of the Carbon-Carbon Bond

In this essay, the classical question of “the influence of the number and kind of substituents on the strength of the C? C bond”, is pursued with the modern tools of contemporary physical organic chemistry. Based on the work of Karl Ziegler, the products and kinetics of thermolysis of a large number of highly branched aliphatic hydrocarbons and phenyl- or cyano-substituted derivatives were investigated. For each class of compounds, a linear relationship was found between the free enthalpy of activation of the homolytic cleavage of the weakest C? C bond and the strain energy in the ground state. These relationships permitted a quantitative separation of steric and electronic effects on the cleavage of C? C bonds. The influence of the size of the substituent groups on bond angles, bond lengths, and the conformational behavior of model compounds was studied by means of experimental structure determinations and force field calculations. C? C bond lengths up to 164 pm, bond angles at tetracoordinate carbon as large as 126°, and unusual eclipsed and gauche preferred conformations were found.