Lithium benzenethiolate CH3CH2CH2CH2LiButyllithium
(g)The starting material is a p-toluenesulfonate ester. p-Toluenesulfonates are similar to alkyl halides in their reactivity. Substitution occurs; a butyl group from lithium dibutylcuprate replaces p-toluenesulfonate.
Phenyl Isocyanate with 1- and 2-Butanol
14.21(a)Meparfynol is a tertiary alcohol and so can be prepared by addition of a carbanionic species to a ketone. Use the same reasoning that applies to the synthesis of alcohols from Grignard reagents. On mentally disconnecting one of the bonds to the carbon bearing the hydroxyl group we see that the addition of acetylide ion to 2-butanone will provide the target molecule.
14.18In the solutions to this problem, the Grignard reagent butylmagnesium bromide is used. In each case the use of butyllithium would be equally satisfactory.
Sodiumacetylide 2-Butanone Meparfynol (94%)
By retrosynthetically disconnecting the butyl group from the carbon that bears the hydroxyl substituent, we see that the appropriate starting ketone is 2-butanone.
O3-Hexanone XMg Butylmagnesium halide
The phenyl substituent can be introduced either cis or trans to the tert-butyl group. The two alcohols are therefore stereoisomers (diastereomers).