Details
- Autor(en) / Beteiligte
- Titel
- Stereo-chemical control of organic reactions in the interlamellar region of cation-exchanged clay minerals
- Ort / Verlag
- ProQuest Dissertations & Theses
- Erscheinungsjahr
- 2015
- Quelle
- ProQuest Dissertations & Theses A&I
- Beschreibungen/Notizen
- Carbene intermediates can be generated by thermal, photochemical and transition metal catalysed processes from diazoalkanes. The carbene intermediates are very reactive and can add across double bonds to give 3-membered rings (cyclopropanes), insert into -OH bonds to give esters or ethers and insert into neighbouring -C-H bonds to give 4 or 5-membered rings, such as β- and γ-lactams or γ-lactones. Copper salts and complexes were amongst the first catalysts to be used for carbene generation from diazoalkanes. However, current tendencies are to use very expensive, especially, platinum group salts and complexes to generate the carbene intermediates, as yields and specificity tend to be higher. We have found that Cu²⁺-exchanged clay minerals (e.g. Wyoming bentonite) and zeolites (zeolite A), have proven to be very competitive in yield with such transition metal catalysts and they have the added advantage that the restricted reaction space within the zeolite pore or clay interlayer favours the more planar/less bulky product. With the clay minerals, when the layer spacing is kept low by judicious choice of mineral or solvent, the selectivity is improved. Herein we report a wide range of carbene addition (cyclopropane formation) and -C-H insertion reactions (β-lactam, γ-lactam and β-lactone formation) catalysed by the Cu²⁺-exchanged clay minerals and the stereochemical consequences of carrying out the reactions within the clay interlayer. Preliminary studies on the successful formation of aziridines from azides via nitrene intermediates with Cu²⁺-exchanged clay minerals are also reported.