STRAIN ENERGIES IN [N]TRIANGULANES AND SPIROCYCLOPROPANATED CYCLOBUTANES - AN EXPERIMENTAL-STUDY

被引:56
作者
BECKHAUS, HD
RUCHARDT, C
KOZHUSHKOV, SI
BELOV, VN
VEREVKIN, SP
DEMEIJERE, A
机构
[1] UNIV FREIBURG,INST ORGAN CHEM & BIOCHEM,D-79104 FREIBURG,GERMANY
[2] UNIV GOTTINGEN,INST ORGAN CHEM,D-37077 GOTTINGEN,GERMANY
关键词
D O I
10.1021/ja00153a006
中图分类号
O6 [化学];
学科分类号
0703 ;
摘要
The enthalpies of formation for trispiro[2.0.0.2.1.1]nonane (3), [3]rotane (4), n-heptyl[3]rotane (6), spiro-[2.3]hexane (7), and the isomeric dispiro[2.0.2.2]octane (8) and dispiro[2.1.2.1]octane (9), as well as [4]rotane (10), have been determined by measuring their heats of combustion in a microcalorimeter; these values and the strain energies (SE) derived from them are compared with values from MM2/MM3 calculations. The results confirm previously reported theoretical and experimental values for spiropentane and establish an additivity scheme for strain energies in all sorts of [n]triangulanes, with an excessive strain energy increment of 8.6 kcal/mol per spiro carbon atom. Such an additional strain increment is virtually nonexistent for 7 (0.8 +/- 0.4 kcal/mol), 8 (0.6 +/- 0.2 kcal/mol), and 9 (0.3 +/- 0.3 kcal/mol) but is significant for 10, with Delta SE = 2.4 +/- 0.5 kcal/mol. Therefore, a simple additivity of strain energies without an excess increment can be employed for spirocyclopropanated cyclobutanes as well as larger rings including [n]rotanes (n > 4).
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页码:11854 / 11860
页数:7
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