[4 + 2]‐Cycloadditionen mit Übergangsmetall‐koordinierten Heteroalkenen: Einfluß der Koordination auf die Stereoselektivität der Cycloaddition

Abstract

4 + 21 Cycloadditions with Transition-Metal-Coordinated Heteroalkenes: The Influence of the Coordination on the Stereoselectivity of the Cycloadditfon Pentacarbonyl(thiobenzaldehyde), -(selenobenzaldehyde), and contrast to the endo selectivity observed in the reactions of 2 -(diphenyl selenoketone) complexes (CO),M[X = C(Ph)R] [R = and 4 with uncomplexed thio-and selenoaldehydes, the ad-H. M = W, X = S (la), Se (lb); M = Cr, X = S (lc), Se (ld); ditions of 2 and 4 to la-d are exo selective. However, the R = Ph: M W, X = Se (1 e)] react with cyclopentadiene (2) reactions of pentamethylcyclopentadiene (6) with 1a.b to form

Metal-Assisted Cycloaddition Reactions in Organotransition Metal Chemistry

“…The extreme reactivity of the free ligands is attenuated, and the complexes 96 can be easily handled. They have been used as convenient sources of CS, CSe, and CTe bonds to synthesize heterocyclics via [4+2] cycloaddition reactions with a variety of open chain and cyclic dienes. ,,− An example is given in eq 87. When unsymmetrically substituted dienes are used, both isomeric cycloadducts are obtained with regioselectivities ranging from 2.4:1 to 19:1.…”

The coordination chemistry of the C:S function. 9. Synthesis of cationic ruthenium thiobenzaldehyde complexes through .beta.-hydride abstraction

“…Faculty of Science Hiromi Tobita TohokU University Hiroshi Ogino* Aoba-ku, Sendai 980, Japan Received September 5,1991 Synthesis of Cationic Ruthenium Thiobenzaldehyde Complexes through j9-Hydride Abstraction1…”

“…For reasons of clarity only C(ipso) of the phenyl groups on phosphorus is shown. Selected bond distances (in A) and angles (in deg) (standard deviations in parentheses): Ru-Pl = 2.296 (1), Ru-P2 = 2.301 (1), Ru-S = 2.314 (1), Ru-ring centroid = 1.882 (1), S-C6 = 1.632 (5): Pl-Ru-P2 = 83.78 (4), Pl-Ru-S = 89.71 (5), P2-Ru-S = 89.30 (4), Ru-S-C6 = 112.0 (2), S-C6-C61 = 126.2 (4).…”

“…The structure assignment of adducts 5 is based on comparison of their NMR data with those of the closely related pentacarbonyltungsten complexes. 5 Both phosphorus nuclei at ruthenium are diastereotopic since the addition of cyclopentadiene creates a stereocenter at the thioaldehyde carbon. The resonance of the proton at this carbon occurs around 3.8 ppm in all three cases, which seems to indicate that proton and aryl group of the former thioaldehyde occupy endo and exo positions, respectively, on the bicyclic ligand.5 A final proof of this assignment, however, will have to await a crystal structure determination of one of these compounds.…”

Synthesis and structure of mixed-ligand iron-sulfur cubane-like clusters [(.eta.-C5Me5)3(Ph2C2S2)Fe4S5]n (n = O and 1+)

“…Faculty of Science Hiromi Tobita TohokU University Hiroshi Ogino* Aoba-ku, Sendai 980, Japan Received September 5,1991 Synthesis of Cationic Ruthenium Thiobenzaldehyde Complexes through /8-Hydride Abstraction1…”