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Design and Synthesis of α ‐Diketones. The Cyclobutane‐1,2‐dione Chromophore: Synthesis, Dienophilic Reactivity and Electronic Properties of Cyclobutenedione and Polycyclic Cyclobutanediones [1]
Author(s) -
Albert Bernhard,
Heller Constanze,
Iden Rudiger,
Martin Georg,
Martin HansDieter,
Mayer Bernhard,
Oftring Alfred
Publication year - 1985
Publication title -
israel journal of chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.908
H-Index - 54
eISSN - 1869-5868
pISSN - 0021-2148
DOI - 10.1002/ijch.198500013
Subject(s) - chemistry , reactivity (psychology) , cyclopentadiene , cyclobutane , steric effects , mndo , chromophore , stereoselectivity , selectivity , acenaphthylene , substituent , condensation , context (archaeology) , organic chemistry , stereochemistry , molecule , ring (chemistry) , phenanthrene , catalysis , paleontology , medicine , alternative medicine , pathology , biology , physics , thermodynamics
A new synthesis of cyclobutenedione (1) is described. It is found that the tricyclic cyclobutanedione 3 splits into 1 and cyclopentadiene if subjected to flash pyrolysis conditions. The dienophilic reactivity of 1 allows the construction of various polycyclic cyclobutanediones, such as 3–5 and 12–14. Other new polycyclic diones, like 9–11, 15 and 16 are prepared by means of the acyloin condensation. The low stereoselectivity of 1 with cyclopentadiene is compared with the selectivity of other cyclobutenes, and the results are placed in the context of secondary interactions and steric hindrance. The unusual colour properties of these diones, from colourless 1 to blue 6 are investigated by means of photoelectron spectroscopic measurements and semi‐empirical calculations (MNDO, HAM/3, CNDO/S‐CI).