Functionalized chloroenamines in aminocyclopropane synthesis IV A synthesis for bicyclic lactams from carbamoylated chloroenamines - the result of a tandem ring contraction - cyclization process
✍ Scribed by Elmar Vilsmaier; Rainer Adam; Peter Altmeier; Joachim Fath; Hans-Josef Scherer; Gerhard Maas; Oliver Wagner
- Book ID
- 104204625
- Publisher
- Elsevier Science
- Year
- 1989
- Tongue
- French
- Weight
- 1003 KB
- Volume
- 45
- Category
- Article
- ISSN
- 0040-4020
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✦ Synopsis
Reaction of N-tosplcarbamoylated chloroenamines 6b-d with sodium cyanide in acetonitrile gave 1n.3.03bicyclic lactams 8b-d instead of the expacted [n.l.O]bicyclic compounds of type 7. X-ray structure analyses of 8b-d established an uniform cis-anellation of the pyrrolidone system and an uniform exo-position of the morpholino moiety. A similar formation of a l&t* was &observed upon thG reaction of the carbamoylated .chloroene&nee 6b and 11 with sodium .borohyd,ride. In the case of 11 an endo-morpholino Product 12 could be isolated which rearranged to the 'la&e stable exo-morPholino bicytzlic system 13 upon heating. 6b directly Provided the thermodynemically controlled exo-mqrpholino isomer 10. Using LiAlHa as hydride reagent converted 6a-c into aminocyclopropanes 2h-c; the carbamayl moiety, thereby, simultaneously was reduced to an aminomethyl group. A bicyclo[2.1.0)Pentyl morpholine 204, accessible by this method, isomerized into a cyclopentenyl morpholine 22 upon heating in the Presence of acid. 8, ' IO, 12 and 13 could be regarded as subsequent Product of Primarily formed aminocycloproPane derivatives 2. A ;=;t:rn ring contraction -cyclization Process better seems to explain at the formation of the Cn.3.0lbicyclic laothms 8 from chloroenamines 6 and cyanide. Reaction of chloroenamines 1 with succinimide yielding aminobicycloalkane carboxamides 2 and thermolysis of the latter in a homoenamine type reaction Provides an easy route to bicyclic lactams 3.' Ring opening of 2 generating zwitterion 4, subsequent ringclosure of 4 Producing a lactam, elimination of succinimide and isomerization of the CC-double bond are discussed as intermed-J?