Zur Chemie einiger verbrückter Bicyclo[1.1.0]but‐1(3)‐en‐Derivate

Abstract

Whereas 3, 4 and 5 could be trapped below 0°C without change of the carbon skeleton, above 20 "C 4 partially isomerized to benzocycloheptatetraene 7. The analogous rearrangement of 3 to give 1,2,3-cyclohexatriene 6, however, was not observed even at 150°C.Wir haben vor kurzem iiber Erzeugung und Abfangreaktionen des Tricycl0[4.1.0.0~~~]hept-l(7)-ens (1) 5, und iiber die Umlagerung dieses Briickenkopfolefins zum 1,2,3-Cycloheptatrien (2) berichtet ' ). In dieser Studie dehnen wir unsere Untersuchungen auf die Systeme 3-5 aus. Es galt vor allem festzustellen, ob sich diese reaktiven Zwischenstufen auf ahnliche Weise wie 1 erhalten und abfangen lieWen und unter welchen Bedingungen sie zu den entsprechenden 1,2,3-Butatrienen 6 -8 a isomerisierten. A. Synthese der AusgangsprodukteEs lag nahe, das bei der Synthese von 1 bewahrte Verfahren auf die Darstellung der Modelle 3-5 zu iibertragen. Die bekannten Bicyclo[l.l.0]butane9a-lla7-9) wurden jeweils am Briickenkopf mit n-Butyllithium (BuLi) zu den lithiumorganischen Zwischenprodukten 9b, 10b und l l b und c metalliert und diese mit pToluolsulfonylchlorid in die entsprechenden Chlorderivate iibergefiihrt").

Synthesis and Applications of Bicyclo[1.1.0]butyl and Azabicyclo[1.1.0]butyl Organometallics

“…In their studies on the synthesis of the highly reactive bicyclo[1.1.0]but‐1(3)‐ene fragment ( 25 ), Szeimies and coworkers demonstrated, for the first time, the use of organolithium 23 as an intermediate in the synthesis of chloro‐, bromo‐ and iodo‐substituted bicyclo[1.1.0]butanes ( 24 , Scheme 5 ). [ 60 , 71 , 72 , 73 , 74 , 75 , 76 ] This was achieved in moderate to low yields using TsCl, TsBr and iodine electrophiles respectively. The resulting bicyclo[1.1.0]butyl halides 24 a – 24 m were shown to eliminate upon exposure to base (or CsF in the case of silylated bicyclo[1.1.0]butanes) to access the targeted strained alkenes ( 25 ).…”

The Synthesis and Chemistry of 1,3‐Bridged Polycyclic Cyclopropenes: 8‐Oxatricyclo[3.2.1.02,4]octa‐2,6‐dienes

“…3 Both 1,2-and 1,3-fused bicyclic cyclopropenes, which are more energetic than cyclopropene itself, have been well studied. 3,4 Pioneering work in highly strained cyclopropenes with various polycyclic frameworks done by Szeimies has led to some important studies of dehydroquadricyclane (1), 5 tetracyclo[4.1.0.0 2,4 .0 3,5 ]hept-3-ene (2), 6 tricyclo[3.1.0.0 2,6 ]hex-1(6)-ene (3), 6 and tricyclo[4.1.0.0 2,7 ]-hept-1(7)-ene (4). 7 There are five 1,2-fused tricyclics with a cyclopropene fused to a bicyclic ring skeleton, tricyclo-[3.2.…”

1,2-Bridged Tricyclic Cyclopropenes: Tricyclo[3.2.1.02,4]octa-2(4),6-diene and Tricyclo[3.2.1.02,4]oct-2(4)-ene

“…Although highly strained bicyclic cyclopropenes have been studied very thoroughly, the synthesis of polycyclic 1,2-bridged cyclopropenes is rare and their chemistry little understood. Pioneering work in highly strained cyclopropenes with various polycyclic frameworks done by Szeimies has led to some important studies of dehydroquadricyclane ( 1 ), tetracyclo[4.1.0.0 2,4 .0 3,5 ]hept-3-ene ( 2 ), tricyclo[3.1.0.0 2,6 ]hex-1(6)-ene ( 3 ), and tricyclo[4.1.0.0 2,7 ]hept-1(7)-ene ( 4 ) but the stereochemistry of this Diels−Alder adduct was not clarified.…”