Über cis‐ und trans‐1,2‐Dimethyl‐cyclopropan‐1,2‐dicarbonsäure

Abstract

Bei einer systematischen Untersuchung uber die thermische Zersetzung von Pyrazolin-carbonsaureestern I) waren u. a. auch die in der Uberschrift genannteu Sauren erhalten worden, die aus den fruher angegebenen Griinden2) einer genaueren Untersuchung wert erschienen.Bemerkenswert war zunachst, daB beide Sauren verschieden waren von einer bereits langer bekanntenverbindung, die in der Literatur gleichfalls unter dem Namen einer 1,2-Dimethyl-cyclopropan-l, 2-dicar6onsGure geht. Der Diathyl-

Involvement of azomethine ylides in the thermal rearrangement of aziridinyl ketones to pyrroles

“…3, X = 0 favorable for overlap of the developing p orbitals derived from the cyclopropane ring bond with the olefinic group and also the developing p orbital derived from the C-H bond. The selection rules for these homodienyl [1,5]-hydrogen shifts are similar to those for 1,5-dienyl shifts and predict that suprafacial migration of the hydrogen atom is a thermally allowed process.…”

“…At least three determinations were made at each temperature. In connection with our interest4•5 in the limits of Bredt's rule in caged tricyclic systems, we have investigated the decomposition of 3-homoadamantyl acetate (1). There has been considerable, recent activity aimed at the generation of bridgehead olefins.6™9 Various techniques have been used to produce highly strained alkenes, including Hofmann elimination,6 bisdehalogenation of vicinal dihalides,7 rearrangement of bridgehead carbenes,8 and perester thermolysis.^However, we have found no reports10 on the decomposition of bridgehead esters to give "anti-Bredt's rule" olefins.…”

Syntheses Of Alkylated Alkanedioic Acids

“…A cyclic structure that can be readily opened because of its high strain is the cyclopropane ring. For example, the trans-anhydride of 1,2-dimethyl-1,2cyclopropanedicarboxylic acid forms (38) a polymeric product on boiling for 1 hr. with acetyl chloride.…”

Preparation and Thermal Decomposition of Selected Pyrazolines.

“…In a series of papers published between 1929 and 1934 von Auwers and coworkers (8), (10), (11), (12), (14) clearly demonstrated the existence of both t. 1 -and t. 2 -pyrazolines.…”