Reactions of trans-5-Palladatricyclo[4.1.0.02,4]heptanes: Stereoselective Formation of Highly Substituted 1,1′-Bi(cyclopropyl) Compounds and (3Z)-1,3,5-Hexatrienes

✍ Scribed by A. Stephen K. Hashmi; Frank Naumann; Andreas Rivas Nass; Alexander Degen; Michael Bolte; Jan W. Bats

• Publisher: John Wiley and Sons
• Year: 1999
• Tongue: English
• Weight: 273 KB
• Volume: 5
• Category: Article
• ISSN: 0947-6539
• DOI: 10.1002/(sici)1521-3765(19991001)5:10<2836::aid-chem2836>3.0.co;2-c

✦ Synopsis

The reaction of the racemic trans-5-palladatricyclo[4.1.0.0 2,4 ]heptanes with hydrogen or NaBH 4 led to (1R*,2R*,1'R*,2'R*)-bi(cyclopropyl) compounds in a highly stereoselective reaction. Reactions with halogens, dibenzoyl peroxide, or cerium(iv) ammonium nitrate (CAN) afforded (3Z)-1,3,5hexatrienes. The stereoselectivity was also high; the only exception was the reaction with bromine in dichloro-methane, where small amounts of the corresponding (3E)-1,3,5-hexatrienes were observed as byproducts. The X-ray structure investigation of one bi(cyclopropyl) compound and one (3Z)-1,3,5-hexatriene proved the stereo-chemical assignments. On the other hand, extensive NMR investigations of two asymmetrical derivatives of the (3Z)-1,3,5-hexatrienes did not allow such an assignment of the double-bond geometry because of the spherical molecular shape of the (3Z)-1,3,5-hexatrienes. Both the reaction with hydrogen and the reaction with oxidants probably proceed through Pd IV intermediates.