Cyclopent-2-en-1-one is a versatile electrophilic cyclopentadiene equivalent in reactions with 1-bromo-1-lithiocyclopropanes. The synthetic sequence (outlined in Scheme 1) has been applied to the synthesis of functionalized 7-X-7,8-dihydrocalicenes 13c (Scheme 3) and 13d (Scheme 4). 7-Bromo-7,8-dihydrocalicene (13d) is considered to be a promising precursor of the so far unknown parent calicene (2). A similar sequence has been realized for 7-(chloromethyl)-7,8-dihydrocalicene (21a, Scheme 5) which, under appropriate conditions, could give 7-methylcalicene (16).
Steuerung einer reaktionsverzweigung durch geeignete phasentransfer-katalysatoren anwendungen der phasentransfer-katalyse 37.
作者:Eckehard V. Dehmlow、Jürgen Wilkenloh
DOI:10.1016/s0040-4039(00)96761-3
日期:1987.1
The influence of phasetransfer catalyst structure on a branching of reaction paths is recorded. An almost complete change-over of mechanisms can be achieved. Reaction of allylbromide with bromoform/sodium hydroxide/catalyst yields carbene adduct and displacement products and . Two new and unusual catalysts, AsPh4Cl and [Ph3PNPPh3] Cl, give substitution: addition ~10:1, wheras NMe4Cl and benzo-15-crown-5