Pyrrolidide als Derivate für die Strukturaufklärung aliphatischer und alicyclischer Carbonsäuren mittels Massenspektrometrie

The pyrrolidide group is, in contrast to the carboxy- and ester groups, capable of inducing strong electron impact fragmentation at the b?- and γ-bonds in complicated alicyclic and aliphatic compounds. The fragments so formed allow certain conclusions concerning the structure in the neighbourhood of the functional group.     

2-羟基-1O,11-二氢-5H-二苯并[a,d]环庚烯-5-酮的合成

以2－羟基苯甲醛和3－甲氧基苯乙酸为原料,经3步反应合成2－羟基－10,11－二氢－5H－二苯并[a,d]环庚烯－5－酮。     

Chirale Alkoxytitan(IV)-Komplexe für enantioselektive nucleophile Additionen an Aldehyde und als Lewis-Säuren in Diels-Alder-Reaktionen

Chiral Alkoxytitanium(iv) Complexes for Enantioselective Nucleophilic Additions to Aldehydes and as Lewis Acids in Diels-Alder Reactions A Number of chiral 1,2-1,3 and 1,4-diols were prepared and used as alkoxy ligands on Ti for enantioselective nucleophilic transfer of methyl, butyl, cyclopropyl, allyl, alkinyl, and phenyl groups to aromatic aldehydes, as well as for the enantioselective[4+2]cycloaddition of acrylate to cyclopentadiene. The 1,2-diols were pinane diol 7 and 1,2:5.6-diacetonide-protected mannitol 9 (Scheme 3) and tartrates. The 1,3-diols were obtained from the yeast-reduction products of 2-oxocyclopentane- and 2-oxocyclohexanecarboxylates and excess MeLi, BuLi, or PhLi (or the corresponding Grignard reagents; see 4–6 .) As 1,4-diols, we used the products 2 and 3 from tartrate acetals and methyl or Pheny1 Grignard reagents, the bis(benzaldehyde) acetal 8 of d-mannitol and o,o'-binaphthol (22). These diols were attached to the Ti-atom by azeotropic removal of i-PrOH from a mixture with [TiCi(i-PrO)₃]. Addition of various organometallic reagents R-metal (metal = Li, BR₃, MgX, MnC1, CuLiR) was followed by combination with aldehydes at – 75^., a warm up period, quenching with aqueous KF solution, and workup (for results see Tables 1–6 and Formulae 17–20 ). The enantiomeric excess of the secondary alcohols obtained varies greatly, certain combinations of chiral ligands, nucleophilic groups, and aldehyde substrates give rise to values as high as 90% ee; see e.g. Table 4. The Ti-complexes of the general formula [Ti(R*O)₂Ci₂] or [Ti(R*O)₂(i-PrO)CI] induced the Diels-Alder addition of methyl acrylate to cyclopentadience to take place at –30^.. The best enantioselectivity (50% ee) was observed with the binaphthol derivative (Table 7). The structures of the complexes involved in these reactions are unknown. The substitution on C(2) of the dioxolanes 2 and 3 (derived from tartaric acid) has a pronounced effect on the selectivities of both reactions studied here (Tables 2, 3, and 7). This remote effect (1,6-distance between the stereogenic acetal-C-atom and the Ti-centers) must be caused by conformational changes in the vicinity of the reactive site, i.e. the Ti? C bond in the nucleophilic addition reactions and the Ti-acrylate-oxygen complexation in the Diels-Alder reaction.     

Über Metall-Stickoxid-Komplexe,XXVII. Nitrosyl-Komplexe von Metallen der Eisengruppe mit Aminosäuren und Aldoximen als Chelatbildnern

In addition to the previously described dinitrosyl complexes of iron and cobalt with anions of 1,3-diketones, salicylic acid etc. nitrosyl complexes which contain the anions of amino acids and aldoximes as chelate ligands have been prepared. Corresponding mononitrosyl chelate complexes of nickel are obtained from the dimeric [Ni(NO)P(C₆H₁₁)₃Br]₂. The infra red spectra and magnetic properties of these compounds are reported.