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Gerhard Hilt

Publications and source records attributed to Gerhard Hilt.

13 recordsLinked to original sources
PubMed2006

Asymmetric cobalt-catalyzed Diels-Alder reactions of a boron-functionalized 1,3-diene with alkynes and allylboration with aldehydes.

[Structure: see text] A cobalt(I)-catalyzed Diels-Alder reaction of a 1-boron-functionalized 1,3-diene is the key step in a one-pot reaction interconnecting three simple starting materials to obtain a multifunctionalized product. This product incorporates a stereogenic quaternary center next to a stereogenic secondary alcohol functionality generated with a very high degree of regio- and diastereoselectivity and good enantioselectivity in the presence of a chiral ligand such as (S,S)-Norphos.

Journal Article↗
PubMed2006

Regioselective carbene insertion on polysubstituted dihydroaromatic compounds.

[reaction: see text] The rhodium-catalyzed CH-insertion reaction of diazo ester derivatives into dihydroaromatic compounds was expanded to the application of various polysubstituted and functionalized 1,4-dienes generated from a cobalt-catalyzed Diels-Alder reaction. The highly regioselective CH-insertion process produces after DDQ oxidation polysubstituted, polyfunctionalized aromatic compounds in good overall yields.

Journal Article↗
PubMed2005

An iron-catalysed chemo- and regioselective tetrahydrofuran synthesis.

An intermolecular ring expansion reaction of an aryl epoxide with several dienes, acrylates, enynes or styrenes under iron catalysis, generated tetrahydrofuran derivatives in a highly chemo- and regioselective fashion. The process could be used in an unprecedented way for the one step synthesis of racemic calyxolane A and calyxolane B with acceptable diastereoselectivity.

Journal Article↗
PubMed2005

A two-step reaction sequence for the syntheses of tetrahydronaphthalenes.

[Reaction: see text] A cobalt(I)-catalyzed Diels-Alder reaction of a boron-functionalized enyne is the key step in a two-step reaction cascade interconnecting four simple starting materials to obtain polycyclic multifunctionalized products in good yields and with a very high degree of diastereoselectivity.

Alkynes↗
PubMed2004

The first broad application of alkynyl sulfides as dienophiles in cobalt(I)-catalyzed Diels-Alder reactions.

The cobalt(I)-catalyzed Diels-Alder reaction of nonactivated aryl alkynyl sulfides with acyclic 1,3-dienes generates dihydroaromatic vinyl sulfides under very mild reaction conditions, and these products can be oxidized with mild oxidants to the corresponding diaryl sulfides in good overall yields. The steric and electronic effects of substituents on the aryl, as well as on the alkynyl, moieties of the aryl alkynyl sulfide are discussed. While the cobalt catalyst system is quite efficient in converting alkynyl sulfides to the Diels-Alder adducts, the transformation of the corresponding aryl alkynyl sulfoxides and sulfones under similar mild reaction conditions gave only moderate yields of the desired adducts.

Journal Article↗
PubMed2002

trans-RuH(eta1-BH4)(binap)(1,2-diamine): a catalyst for asymmetric hydrogenation of simple ketones under base-free conditions.

Reaction of a chiral RuCl2(diphosphine)(1,2-diamine) complex and NaBH4 forms trans-RuH(eta1-BH4)(diphosphine)(1,2-diamine) quantitatively. The TolBINAP/DPEN Ru complex has been characterized by single crystal X-ray analysis as well as NMR and IR spectra. The new Ru complexes allow for asymmetric hydrogenation of simple ketones in 2-propanol without an additional strong base. Various base-sensitive ketones are convertible to chiral alcohols in a high enantiomeric purity with a substrate/catalyst ratio of up to 100 000 under mild conditions. Configurationally unstable 2-isopropyl- and 2-methoxycyclohexanone can be kinetically resolved with a high enantiomer discrimination. This procedure overcomes the drawback of an earlier method using RuCl2(diphosphine)(diamine) and an alkaline base, which sometimes causes undesired reactions such as ester exchange, epoxy-ring opening, beta-elimination, and polymerization of ketonic substrates.

Journal Article↗