Preparation of substituted cyclopentadienyl ligands by nucleophilic addition to substituted fulvenes

• Main Author: Shen, Lihong
• Format: Others
• Published: DigitalCommons@Robert W. Woodruff Library, Atlanta University Center 1990
• Subjects: Chemistry
• Online Access: http://digitalcommons.auctr.edu/dissertations/3188; http://digitalcommons.auctr.edu/cgi/viewcontent.cgi?article=4005&context=dissertations

By modifing the procedure reported by Stone and Little, we have been able to make substituted fulvenes on a large scale and maintain good yield. Treatment of 6-tert-butylfulvene with lithium diethylamine gave, upon work-up, neopentylcyclopentadiene in 83% yield. Treatment of neopentylcyclopentadiene with n-butyllithium followed by zirconium tetrachloride gave [ƞ5-C5H4CH2C(CH3)3]2ZrCl2 in 19% yield. Treatment of 6-tert-butylfulvene with lithium 1,2,3,4-tetrahydroisoquinoline gave, upon work-up, neopentylcyclopentadiene in 71% yield- and a mixture of 3,4-dihydroisoquinoline, 1,4-dihydroisoquinoline and isoquinoline in 72% combined yield. Treatment of 6-methyl-6-phenylfulvene with dilithio-Ɩ-proline at -78 °C gave, upon work-up, a 99% yield of 1-cyclopentadienyl-1-phenylethane, 17.4% ee. Treatment of 6-methyl-6-phenylfulvene with dilithio (s)-(-)-2-pyrrolidone-5-carboxylic acid at -78 °C gave, upon work-up, a 99% yield of 1-cyclopentadienyl-1-phenylethane, 8.7% ee. Treatment of 1-cyclopentadieny-11-phenylethane (8.7% ee) with one equivalent of n-BuLi followed by treatment with lithium cyclopentadienide and ferrous chloride gave, upon work-up, [C5H5][C5H4(CH(CH3)C6H5)]Fe, 10.5% ee. Treatment of 1-cyclopentadienyl-1-phenylethane (17.4% ee) with one equivalent of n-BuLi followed by treatment with cyclopentadienyltitanium trichloride gave, upon work-up, a 48% yield of [C5H5][C5H4(CH(CH3)C6H5)]TiCl2. Treatment of 1-cyclopentadienyl-1-phenyl-ethane (17.4% ee) with one equivalent of n-BuLi followed by treatment with zirconium tetrachloride gave [C5H4(CH(CH3)C6H5)]2ZrCl2 in 78% yield. Treatment of 6-tert-butylfulvene with excess of cyclopentadienyl lithium gave, upon work-up, 1, 1-bis(cyclopentadienyl)-1-tert-butylmethane in 34% yield. Treatment of 1, 1-bis(cyclopentadienyl)-1-tert-butylmethane with two equivalent of methylmagnesium bromide or isopropylmagnesium chloride followed by quenching with D2O gave 1,1-bis(cyclopentadienyl)-l-tert-butylmethane-d2 in 56.9% and 84.1% yield respectively. Treatment of fluorenyl lithium with 6-tert-butylfulvene gave, upon work-up, a 44% yield of 1-cyclopentadienyl-1-fluorenyl-2,2-dimethylpropane as a yellow solid. Treatment of this yellow solid with two equivalent of n-BuLi followed by treatment with zirconium tetrachloride gave a 72% yield of neopentyl(cyclopentadienyl-l-fluorenyl) zirconium chloride.