Propellanes. Part LXXXII. Preparation and Labelling of [20.3.3]Propellane-24,27-dione

✍ Scribed by Pnina Ashkenazi; Jürgen Kettenring; Shmuel Migdal; Arie L. Gutman; David Ginsburg

• Publisher: John Wiley and Sons
• Year: 1985
• Tongue: German
• Weight: 217 KB
• Volume: 68
• Category: Article
• ISSN: 0018-019X
• DOI: 10.1002/hlca.19850680728

✦ Synopsis

The title diketone has been prepared by a synthetic sequence beginning with decane-1 ,lo-dicarboxylic acid.

Introduction. -We wanted to obtain the diketone 8a mentioned in the title in order to attempt the threading of the 22-membered ring in a derivative thereof with an aliphatic chain [2]. The size of the large ring was dictated by the price of the starting material, decane-1,lO-dicarboxylic acid 1 [3]. We believed that the ring size sufficed for our purpose since its CPK model could be assembled. Synthesis. -The starting material 1 was esterified by the classic Fischer method to afford the corresponding dimethyl ester 2 (Scheme I). Another old method [4a] was used to convert this into the half-ester 3. Kolbe condensation using the standard method [S] gave the C,, dimethyl ester 4a, whose corresponding half-ester 5 was also submitted to the Kolbe reaction to afford the C,, dimethyl ester 4b. (The latter, when converted into a [40.3.3]propellane would certainly have a large ring capable of being threaded should this not succeed in the [20.3.3]propellane derivative.) Acyloin condensation of 4a in the presence of Me,SiCl afforded the cyclic C,, acyloin 6a [6] (Scheme 2). Its oxidation [7] gave the corresponding C,, diketone 7a. When the Scheme 1 Kolbe Mr0$(CH2),, COpH -Me02C(CH2)n COpMe 5 4b (n=40)