Synthesis, solid-state structure, and reduction of 1,1-dichloro-2,3,4,5-tetramethylsilole
摘要:
The previously unknown 1,1-dichloro-2,3,4,5-tetramethyl-1-silacyclopenta-2,4-diene (3) was prepared in a three-step synthesis starting from zirconocene dichloride, 2-butyne, and n-butyllithium via bis(cyclopentadienyl)-2,3,4,5-tetramethyl-1-zirconacyclopenta-2,4-diene (1) and 1,4-diiodo-1,2,3,4-tetramethylbuta-1,3-diene (2).3 was characterized by NMR spectroscopy and single-crystal X-ray diffraction. Reaction of the new silole 3 with 4 equivalents of lithium in THF gives the corresponding dianion 4. H-1-, C-13-, and Si-29-NMR chemical shifts of 4 compared with 3 indicate some aromatic character for the ionic species. Trapping of 4 with Me(3)SiCl gives 1,1-bis(trimethylsilyl)-2,3,4,5-tetramethylsilole (5) in quantitative yield.
Formation of 2,6-dioxabicyclo[3.3.0]-octa-3,7-dienes or multiply substituted o-benzoquinones from reactions of 1,4-dilithio-1,3-dienes with dimethyl oxalate
作者:Guoliang Mao、Jiang Lu、Zhenfeng Xi
DOI:10.1016/j.tetlet.2004.08.181
日期:2004.10
Reactions of 1,4-dilithio-1,3-dienes with dimethyl oxalates afforded multiply substituted o-benzoquinones or stereodefined 2,6-dioxabicyclo[3.3.0]-octa-3,7-dienes in good yields.
Stereoselective Synthesis of Polysubstituted 2,5-Dihydrofurans from Reaction of 1,4-Dilithio-1,3-dienes with Aldehydes
作者:Jinglong Chen、Qiuling Song、Pixu Li、Hairong Guan、Xianglin Jin、Zhenfeng Xi
DOI:10.1021/ol0261478
日期:2002.6.1
Reaction of 1,4-dilithio-1,3-diene derivatives with 2 equiv of aldehydes affords polysubstituted 2,5-dihydrofurans in good to high yields with perfect regio- and stereoselectivities. Hexa-2,4-diene-1,6-dialcoholates are proposed as the first intermediates, which undergo a cyclization and subsequent elimination of Li2O to generate the 2,5-dihydrofuran derivatives.