ChemInform Abstract: Spiropentane. 3. Mitt. Synthese von gem.‐Dihalogenspiropentanen.

Abstract

Die nach Literaturangaben dargestellten Methylencyclopropane (I) werden nach dem Verfahren von Doering oder Makosza mit Dichlor‐ bzw. Dibromcarben in die Titelverbindungen (II) übergeführt.

Polylithiumorganic compounds. Part 29: C,C Bond cleavage of phenyl substituted and strained carbocycles using lithium metal

“…The 1 H NMR data was in accordance with reference data. 30 1-Bromo-4,4-diphenylspiropentane. 56 mL of a 1.6 M solution (89 mmol) of n-butyllithium was added to a solution of 30.6 g (80 mmol) of 1,1-dibromo-4,4-diphenylspiropentane in 200 mL of THF and 90 mL of diethyl ether at K100 8C while keeping the temperature of the reaction mixture below K100 8C.…”

“…Cleavage of 1-methyl-3-phenylbicyclobutane (31). The reaction of 31 with lithium metal affords 1,3-dilithio-1-methyl-3-phenylcyclobutane (32) as a mixture of cis/trans-isomers under similar experimental conditions, which were used for 26 in THF as the solvent.…”

“…29 4.2.1. Phenylspiropentane (41a) 30 . Contrary to the reference procedure, 30 1,1-dibromo-4-phenylspiropentane could not be completely reduced to phenylspiropentane using zinc dust and hydrochloric acid, mixtures were obtained instead, therefore, the following two-step procedure was used.…”

“…Phenylspiropentane (41a) 30 . Contrary to the reference procedure, 30 1,1-dibromo-4-phenylspiropentane could not be completely reduced to phenylspiropentane using zinc dust and hydrochloric acid, mixtures were obtained instead, therefore, the following two-step procedure was used. After 45 min at K20 8C 100 mL of a saturated solution of aqueous ammonium chloride and 300 mL of water were added; the aqueous layer was extracted with three portions of diethyl ether.…”

“…Attempted cleavage of 1-lithio-3-phenylbicyclobutane (30). 30 is obtained by metalation of 1-phenylbicyclobutane (26) using t-butyllithium in THF at temperatures between K70 and K40 8C.…”