Cyclobutan‐tetracarbonsäuren‐(1.2.3.4)

Criegee, Rudolf; Höver, Hermann

doi:10.1002/cber.19600931113

Cited by 29 publications

(2 citation statements)

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“…Stecher, Tetrahedron Letters 1967, 3847. [7] A second order asymmetric transformation is indicated in this case; weakly dextrorotatory (36) was obtained from the mother liquors of the brucine salt.…”

Section: ] W Tochtermann K Oppenlander and M Nguyen-duongmentioning

confidence: 93%

“…(potassium iert-butoxide in DMSO) and subsequent hydrogenation t o (6) [*], also by dehydrogenation by chloranil in benzene at 20 O C to (7) 181. Compound (3) does not react with maIeic anhydride at 2OoC, which clearly indicates a distorted 1,3-cyclohexadiene system that can be contained only in the trans-compound.…”

Section: The Constitution Of (3) Is Proved By Basic Isomerizationmentioning

confidence: 99%

See 1 more Smart Citation

Two New Valence Isomers of [12]Annulene

Schröder¹,

Martin²,

Röttele³

1969

Angew. Chem. Int. Ed. Engl.

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+ 2 3 2 3 2 3 2 3 2 2 2 2 2 2 2 2 (3a), X = Br (3b), X = COOH Keeping equimolar amounts of (3b) and brucine in ethanol/ methanol (1 : 1-1 : 2 v,'v) for some time gives a 60 % yieldC71 of a crystalline brucine salt that shows rapid mutarotation in acetone at 20.5 O C (ty2 = 200 sec; extrapolation of the specific rotation to to gives [ C C ] : ;~ = +87 O, changing to -43 O, c = 0.013 g/ml). The dextrorotatory acid can be obtained by dissolving this salt as fast as possible in acetone at -2OOCand precipitating it rapidly with 2N HCI. Solutions of (+)-(3h) in acetone racemize at +20.5 "C with a half-life period of 195 sec; [ o ( ] : : b 5 was +135" after 105 sec (extrapolated to to: [a]::k5 = +190 O, c = 0.02 g/ml). Thence the free enthalpy of activation for ring inversion of (3b) is calculated to be AG.$,, = 20.8 kcal/mole, i.e., (36) is much more mobile than comparable systems 111.

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Section: ] W Tochtermann K Oppenlander and M Nguyen-duongmentioning

confidence: 93%

Section: The Constitution Of (3) Is Proved By Basic Isomerizationmentioning

confidence: 99%