Stereocontrolled synthesis, conformational features, and response to thermal activation of the seven possible bis- and trishomocycloheptatrienes

Abstract

9) We thank Professor Martin Saunders for giving us a copy of this program. (10) Also formed was an unknown roughly equivalent in quantities to the traris-a,(3-unsaturated nitrile and surmised to be one of the /3,7-isomers.(11) (a) E.

Rearrangement of radicals derived from bicyclo[5.1.0]octa-2,4-diene, tricyclo[6.1.0.02,4]nona-6-ene and tetracyclo[7.1.0.02,4.05,7]decane

“…Preparation of Radical Precursors.-We intended to generate the bicyclo[5.l.0)octa-2,4-dienyl radical, with and without a deuterium label, by reduction of the known homotropone (7) with sodium borodeuteride or sodium borohydride and subsequent conversion of the alcohol (8) into the bromide (9a) or chloride (9b) (see Scheme 1). Reaction of (9) with tin-centred radicals would then give (10) and the deuterium label would provide a useful probe of the subsequent rearrangements.…”

Comparative study of syn- and anti-1,5-bishomocycloheptatrien-2-yl radicals and carbocations

“…Concentration and preparative VPC purification showed two products (ratio 85:15) to dominate the mixture (85%). The more rapidly eluted major component (176 mg, 46%) was a colorless oil identified as monochloride 5: IR (neat) 3070, 3000,2920, 2860,1650,1450,1130,825, and 725 cm-1; NMR ¿Me4Si (CCI4) 5.62 (s, 2), 2.53 (d of t, J = 13 and 4 Hz, 1), 2.08-1.03 (br m, 4), 0.80 (d oft, =7 = 7 and 4 Hz, 1), 0.50 (t, J = 5.5 Hz, 1) , and 0.00 (m, 2); 13C NMR (CDCI3) 131.4 (d), 128.9 (d), 41.2 (s), 34.3 (k), 28.7 (d), 25.1 (t), 15.0 (d), 14.2 (t), and 12.8 ppm (d); m/e caled 154.0549, found 154.00554.…”

Synthesis and protonation studies of syn- and anti-2,4-bishomotropone. Comparison with the behavior of epimeric 2,4-bishomocycloheptatrienols under long- and short-lived ionization conditions

“…Presumably in order to achieve enhanced charge dispersal, one of the methylene bridges in 2 is believed to experience subsequent conformational inversion to deliver the more thermodynamically stable and spectroscopically detectable syn isomer 3. The latter constitutes the only example 9 6…”