Paritosh R. Dave

Structure of a Cage Dimer (I) and a Dimer Ketone (II) Formed via Thermal Reaction of Ethyl 3-Phenyl-2-Norbornadienecarboxylate with Pentacarbonyliron

Diethyl 1,14-diphenylheptacyclo(6.6.0.- 02,6.03,13.04, ~ 1.05.9.0 ~0.14)tetradecane_2,10-dicarboxy- late (I), C32H3204, Mr=485.60, triclinic, P1, a= 9.292(2), b=11.823(2), c=13.224(3)A, t~= 66.53 (2), t= 86-80 (2), y= 68.36 (2) °, V= 1231.5(5),~ 3, Z=2, Dx=l.3OMgm -3, 2(MoKt~) = 0.71073 ./~, /t = 0.08 mm -~, F(000) = 512, T= 295K, final R =0.082, wR =0.068 for 2624 ob- served reflections. Diethyl 9-oxo-2fl,7fl-diphenyl-lfl,- 2, 3,4j~,4afl,4bfl, 5 t~,6,7,8 a, 8 aft, 9 amdodecahydro- 1,4: 5,8- dimethanofluorene-3fl,6fl-dicarboxylate (II), C33H3605, Mr=512.64, monoclinic, P2~/n, a=10.206(1), b= 17.853 (2), c= 14.940 (2)A, t= 102.50 (9) ° , V= 2657.6 (4) ,/t 3, Z = 4, D x = 1.28 Mg m -a, 2(Cu Ka) = 1.54178/~, /~ = 0.64 mm -~, F(000) = 1096, T= 295 K, final R =0.046, wR =0.057 for 3114 ob- served reflections. In (I) the cyclotetradecane cage formation occurred such that the two phenyl groups are on adjacent C atoms and all the substituents are cis with respect to one another (C-C-C-C torsion angles are -1.7 and -1.6° for the phenyl-ethoxycarbonyl neighbors and -26.9 ° for the phenyl-phenyl system). In (II) the phenyl groups are cis with respect to their adjacent ethoxycarbonyl neighbors (C-C-C-C tor- sions are -4.6 and -7.1 ° ) but are on opposite sides of the fused ring system. Introduction. As part of a detailed study of the stereochemistry and mechanism of the carbonyliron- promoted coupling of substituted norbornadienes to carbon monoxide (Marchand & Hayes, 1977; Mar- chand, Goodin, Hossain & van der Helm, 1984; Marchand, Earlywine & Heeg, 1986), the thermal reaction of Fe(CO) 5 with racemic ethyl 3-phenyl- 2-norbornadienecarboxylate (Scheme 1) has been investigated. Reactions of this type often proceed with a high degree of regio- and stereoselectivity to afford a variety of products, among which are a heptacyclic cage cyclodimer (Neely, van der Helm, Marchand &