Stereoselective Nucleophilic Addition Reactions of Reactive Pseudopeptides

ChemInform Abstract: Ligand Effects in Grignard Additions.

Ligand Effects in Grignard Additions

Organotitanium reagents in organic synthesis a simple means to adjust reactivity and selectivity of carbanions

Anchimer beschleunigte Homolysen, V. Thermische und Fluoridionen‐katalysierte Umlagerungen von Benzyl)‐[9‐(trimethylgermyl)‐9‐fluorenyl]‐ether

Anchimerically Enhanced Homolyses, V. Fluoride Ion Catalysed Rearrangements of Benzyl 9-(Trimethylgermyl)-9-fluorenyl Ether The thermal rearrangement (homolysis) of the germanium compound 1d into 4d is considerably slower than that of the analogous Si compound 1c. Thus, a correlation is suggested between the velocity of the rearrangement and the strength of the new bond to oxygen. The rearrangement 1d4d is also induced by fluoride ions at room temperature.

Synthesis and Properties of Some Simple Organotitanium Compounds

Before embarking on a detailed discussion of the titanation of carbanions, synthetic and physical organic aspects of several typical organotitanium (IV) compounds shall be surveyed, including thermal stability, aggregation state, X-ray structural data and bond energies. Some of this information is useful in understanding reactivity and selectivity in reactions with organic substrates. Low valent Ti (II) and Ti (III) shall be mentioned only on passing; the interested reader is referred to reviews [1].

Heterotope Wirtmoleküle zur Einlagerung von zwei verschiedenen Gästen

Stereoselectivity in the Addition of Organotitanium Reagents to Carbonyl Compounds

Although great strides have been made in the area of stereoselective C—C bond forming reactions [1], many problems persist. Early studies concerning chemo- selective reactions of organotitanium reagents (Chapter 3) suggested that they might also behave stereoselectively in relevant cases. In fact, the first such observation goes back to 1979 when it was noted that dichlorodi- methyltitanium (2) adds to the ketone 1 in CH2C12 to produce a mixture of tertiary alcohols 4/5 instead of the desired (±) cuparene (3) [2, 3]. The striking aspect of this transformation is the high disastereoselectivity in favor of 4. Methyllithium shows the opposite stereoselectivity (4:5 = 34:66), in line with the s…

Cationic mono- and bi-nuclear iron complexes as Lewis acid catalysts in Mukaiyama reactions

Organometallic Lewis acids derived from photolysis of mono- and bi-nuclear cationic iron carbonyl complexes function as excellent catalysts for the Mukaiyama aldol reaction.

ChemInform Abstract: Stereoselective Nucleophilic Addition Reactions of Reactive Pseudopeptides.

Kronenether mit einem Lewis-sauren Zentrum, eine neue Klasse heterotoper Wirtmoleküle

Rates of Reactions

Inspite of the fact that many organotitanium compounds are well characterized, the number of kinetic studies is limited. This chapter deals primarily with such efforts directed toward elucidating the intricacies of carbonyl addition of CH3Ti(OCHMe2)3. Various other kinetic processes are also briefly discussed (Section 4.2).