Bredt, Julius

Bredt s rule (Julius Bredt, 1924) is a qualitative generalization that bridged, bicyclic ring systems cannot have a double bond at the bridgehead. This rule does not apply to fused or large-member ring systems. 

The interest of the early synthetic and structural conundrums posed by camphor (40) (cf. Vol. 2, p. 149) are well illustrated in a profile of Julius Bredt. Three unusual bicyclo[2.2.1]heptenes, 772, have been characterized from lavender oil there is nothing spectacular about their synthesis, since they are... 

Julius Bredt (1855-1937) observed that molecules containing twisted carbon-carbon double bonds are prohibited because alkenes favor planar double bonds with bond angles near 120°. Alkynes, such as acetylene (HC=CH), favor linear geometry (180°) about their triply bonded carbons. The benzene ring was shown in the 1930s to be flat. 

Otto Wallach (1847-1931) (laureate of the 1910 Nobel Pri2e for Chemistry) and Konrad Julius Bredt (1855-1937) recognised at the beginning ofthelast century thatterpenes are formed from Cs-buUding blocks (Fig. 7.13) semiterpenes (C5), monoterpenes (Cm), sesquiterpenes (C15), diterpenes (C2o)> sesterterpenes... 

Ber.y 1893, xxvi, 3047 1894, xxvii, 2092 1895, xxviii, 316 Ann. 1896, ccxcii, 55 (121) 1898, ccxcix, 131. Julius Bredt (Berlin, 29 March 1855-Honnef (Rhine), 21 September 1937), professor in the Technical High School, Halle. 

It was noticed in 1924 by the German chemist Julius Bredt (1855-1937) that one structural type was conspicuously absent among the myriad compounds isolated from sources in Nature. There seemed to be no double bonds attached to the bridgehead position in what are called bridged bicyclic molecules. The bridgehead position is the point at which the bridges meet (Fig. 3.44). Apparently, great... 

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