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Zur Reaktionsweise von Enaminen mit Cyclopropenonen I . Einsatz von Cyclododecanon‐Enamin
Author(s) -
Steinfels M. A.,
Dreiding A. S.
Publication year - 1972
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/hlca.19720550247
Subject(s) - chemistry , yield (engineering) , wittig reaction , medicinal chemistry , lithium aluminium hydride , lithium (medication) , bicyclic molecule , stereochemistry , hydrolysis , organic chemistry , medicine , materials science , metallurgy , endocrinology
Monomethyl‐, dimethyl‐, di‐ n ‐propyl‐ and diphenyl‐cyclopropenone ( 6 to 9 ) have been reacted with 1‐(N‐pyrrolidino)‐cyclododecene ( 5 ) and three types of products isolated. The major products (40–7% yield) were shown to have the 3 ‐(cyclododec‐1′‐ E ‐enyl) Z ‐/or E ‐acryl‐pyrrolidide structure ( 12 , 13 / 14 , 15 / 16 , 17 ) by their spectral properties and lithium aluminium hydride reductions as well as, in one case ( 13 ), by an alternative synthesis of a stereomer ( 34 ) via 1‐(cyclododec‐ E ‐ene)‐carboxaldehyde ( 29 ) and a Wittig reaction. These ‘amides’ are the result of a novel reaction, called ‘ C , N ‐ insertion ’. In the reactions of the symmetrical cyclopropenes 7 to 9 with 5 , the minor products (6–10%) proved to have the 2,4‐disubstituted cyclopentadeca‐4‐ E ‐en‐1,3‐dione structures 38 to 40 . These ‘β‐diketones’ are considered to be the hydrolysed forms of the intermediate 1‐(N‐pyrrolidino)‐cyclopentadeca‐1,4‐dien‐3‐ones ( 45 ).They are formed by reactions (called ‘C,C‐insertions’) , which represent the first cases of direct ring expansions by three carbon atoms. Such ‘C,C‐insertions’ have been postulated previously by other authors. However, their products do not behave like precursors of our ‘β‐diketones’ but rather like our ‘amides’. It is proposed therefore, that a reinterpretation of these reactions in the literature must be considered in the light of our ‘C, N‐insertion’. In one reaction ( 8 + 5 ) a bicyclo[10. 3. 0]pentadeca‐12‐en‐14‐one dericative 42 was found in 10% yield. This type of product and reaction (called ‘condensation’) has been reported previously. A suggestion is made for a systematic representation of the several types of reactions, which cyclopropenones can undergo with enamines. – Mixing 9 + 5 in the cold produced an intermediate, which insomerised on heating to the ‘amide’ 17 . Its properties are compared with those of recently described similar ‘primary adducts’ and the latter are reexamined in the light of the new product interpretations reported in this paper. A novel structure is considered for this intermediate, that a of cycle ‘ammonium acylid’ 51 . An attempt is made at the formulation of other possible intermediates.