Novel Organogermanium Compounds via Metalation of 3-Trimethylsilyl-3-ethoxycarbonylcyclopropene Derivatives

Abstract

Preparation and full spectroscopic characterization of novel trimethylgermyl derivatives of 3-trimethylsilyl-3-ethoxycarbonylcyclopropenes (4−7) and 1,1-bis(trimethylgermyl)-3-trimethylsilyl-3-ethoxycarbonylallene (8) are described.

Clinical and placental characteristics in four new cases of twin anemia–polycythemia sequence

“…Da die Alkenylwasserstoffatome von Cyclopropenen saurer sind als die von ungespannten Alkenen, führt die Deprotonierung zu einer interessanten Carbanionen‐Quelle. Allerdings trat bei Versuchen zur direkten Metallierung des estersubstituierten Cyclopropens 12 eine schnelle Ringöffnung unter Bildung des umgelagerten Produkts 14 ein (Route B, Schema ) 26. Fox et al.…”

Studies on the Stability of Cycloprop-2-ene Carboxylate Dianions and Reactions with Electrophiles

“…These methods provide access to chiral cyclopropenes from terminal alkynes, but there are relatively few methods that provide access to chiral cyclopropenes with two alkene substituents. This discrepancy prompted Eckert-maksic,6a–c Lam,6d Gevorgyan7 and us8 to investigate protocols for converting “terminal” cyclopropenes into “internal” cyclopropenes 9. Gevorgyan and coworkers have described an elegant, Pd-catalyzed method for accessing chiral, internal cyclopropenes by the direct arylation of alkyl cycloprop-2-ene carboxylates 7a.…”

“…It is well established that cyclopropenes are acidic at the vinylic position and can be functionalized through deprotonation/electrophilic capture 10. Eckert-Maksic and coworkers demonstrated that alkyl cycloprop-2-ene carboxylates can be generated and captured by silyl and germanyl electrophiles that were available for in situ reactivity 6a–c. However, that protocol was limited to electrophiles that could be introduced prior to the introduction of base: the anions underwent ring-opening fragmentation when the electrophile was introduced subsequent to the addition of base.…”

“…However, that protocol was limited to electrophiles that could be introduced prior to the introduction of base: the anions underwent ring-opening fragmentation when the electrophile was introduced subsequent to the addition of base. Lam has recently described a Cu-catalyzed method for silylation of cyclopropenes using TMSOTf,6d and a KF mediated method for the stannylation of cyclopropenes by Bu 3 SnC 2 F 5 6e. The cyclopropenes produced by the latter method can be further elaborated via Stille couplings 6e.…”

“…Lam has recently described a Cu-catalyzed method for silylation of cyclopropenes using TMSOTf,6d and a KF mediated method for the stannylation of cyclopropenes by Bu 3 SnC 2 F 5 6e. The cyclopropenes produced by the latter method can be further elaborated via Stille couplings 6e. Our group described a procedure for anion formation/capture that utilized the dianions of cycloprop-2-ene carboxylic acids.…”