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Bis-[2.X]-σ-homobenzenes

✍ Scribed by Horst Prinzbach; Hans-Peter Schal; Dieter Hunkler

Book ID
104238178
Publisher
Elsevier Science
Year
1978
Tongue
French
Weight
220 KB
Volume
19
Category
Article
ISSN
0040-4039

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✦ Synopsis

The geometry of the cis-bin-(l) and cis-tried-homobenzenes ( 2) is unusually favourable for their [28+2s+2s]-cycloreversion. For that reasou, it is argued, the "ho-

moaromatic" stabilisatiou in their homobeuzeuoid transition states is remarkable eveu in cases with relatively uufavourable three-membered-riug compoueuts X, Y, Z (e.g. oxygen)

  1. . Au obvious test for this argument is the successive replacement of the three-membered rings in (1) and ( 2) by cyclobutaue rings as in the series (3) to

X YP -Bis -12.11

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Dihydroazocines and hydrooxocins, which are sought as the conjugate acids of novel 10X-heterocinyl-anions, are made available via cis-aza/oxa-bis-o-homobenzenes from 7-cyanotropilidene. The (Y2+o2+a2)-cycloreversion of cis-aza/oxa-bis-o-homobenzenes A is established as an efficient access to 1,4-dih

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rated without material loss by flash chromatography. The bismesylates 19 b/20 b, prepared under standard conditions in 85-90% yield, can be converted into the tetracyclic aziridine 21 b (70-85%) under the conditions used for 5 b (1 0 mmol, triphenylphosphane/THF). Cyclization of 21 b to 22 proceeds

Tris-[2.21]- and tris-[2.2.2]-σ-homobenz
Tris-[2.21]- and tris-[2.2.2]-σ-homobenzenes
✍ Gabrielle McMullen; Gottfried Sedelmeier; Rainer Hildebrand; Hans Fritz; Horst P 📂 Article 📅 1979 🏛 Elsevier Science 🌐 French ⚖ 187 KB

Tris-[2.2.1]-and tris-[2.2.2] -o-homobenzenes are synthesised by reaction of l,l'-bicyclobutenyl with appropriate dienophiles and hydrogenation of the adducts. 'X' 1 1 2 should be attained by means of the [2.2.1]-and [2.2.2]-homoand 12-membered transition states resp. In view of the conthe area of c