144657-41-0Relevant articles and documents
The synthesis of norbornanes with functionalized carbon substituents at a bridgehead. 1-(3-Oxonorborn-1-yl)ethanone and 1-(3-oxonorborn-1-yl)-2-propanone
Yates, Peter,Kaldas, Magdy
, p. 1492 - 1505 (2007/10/02)
Treatment of 2-norbornene-1-carboxylic acid (7) with one equivalent of methyllithium in ether followed by a second molar equivalent after dilution with tetrahydrofuran gave 1-(norborn-2-en-1-yl)ethanone (10) and only a trace of the tertiary alcohol 11.Reaction of 7 with formic acid followed by hydrolysis gave a 4:3 mixture of exo-3- and exo-2-hydroxynorbornane-1-carboxylic acid (16 and 17), whereas oxymercuration-demercuration gave gave only the exo-3-hydroxy isomer 16.Oxidation of 16 and 17 gave 3- and 2-oxonorbornane-1-carboxylic acid (27 and 29), respectively.Oxymercuration-demercuration of 10 gave exclusively 1-(exo-3-hydroxynorborn-1-yl)ethanone (30), which was also prepared by treatment of 16 with methyllithium in analogous fashion to that used for the conversion of 7 to 10.Oxidation of 30 gave 1-(3-oxonorborn-1-yl)ethanone (1).Dehydrobromination of exo-2-bromonorbornane-1-acetic acid and dehydration of 2-hydroxy-norbornane-2-acetic acid derivatives gave 1-(norborn-2-ylidene)acetic acid derivatives to the exclusion of norborn-2-ene-1-acetic acid derivatives.Treatment of exo-5-acetyloxy-2-norbornanone (52) with ethyl bromoacetate and zinc gave ethyl exo-5-acetyloxy-2-hydroxynorbornane-exo- and endo-2-acetate (53 and 54).Reaction of 53 with hydrogen bromide gave initially ethyl endo-3-acetyloxy-exo-6-bromonorbornane-1-acetate (59), which was subsequently converted to a mixture of 59 and its exo-3-acetyloxy epimer 61.Catalytic hydrogenation of this mixture gave a mixture of ethyl endo- and exo-3-acetyloxynorbornane-1-acetate (62 and 63).Basic hydrolysis of this gave a mixture of the corresponding hydroxy acids, 70 and 71; the former was slowly converted to the latter at pH 5.Oxidation of the mixture of 70 and 71 gave 3-oxonorbornane-1-acetic acid (72).Treatment of the mixture with methyllithium as for 16 gave a mixture of 1-(endo- and exo-3-hydroxynorborn-1-yl)-2-propanone (73 and 74), which was oxidized to 1-(3-oxonorborn-1-yl)-2-propanone (2).Reaction of exo-2-hydroxynorbornane-1-acetic acid lactone (75) with methyllithium in ether gave 1-(exo-2-hydroxynorborn-1-yl)-2-propanone (76), which on oxidation gave the 2-oxo isomer 78 of 2.
