Baylis-Hillman-type C-C bond formation and olefin diamination reaction

This thesis described new methodologies for Baylis-Hillman-type C-C bond formation and olefin diamination reaction. The Baylis-Hillman-type reaction was developed using a,â-unsaturated cycloketone and S-ethyl thioacrylate as the Michael-type acceptors with diethylaluminum iodide alone as the promoter. Direct diamination of enones was developed using N,N-dichloro-2-nitrobenzenesulfonamide (2-NSNCI2) as the electrophilic nifrogen source.

The Baylis-Hillman-type reaction between a,â-unsaturated cycloketone or a,â-unsaturated S-ethyl thioacrylate and aldehydes has been achieved using diethylaluminum iodide as the promoter without the direct use of any Lewis bases. The reaction showed a good scope of substrates, and aldehydes which failed to give desired Baylis-Hillman products under our previous TiCl4-based conditions can be successfully used as the electrophiles to give good yields. The reactions proceeded to completion at 0 °C in CH2CI2 within 7-24 hours without the protection by inert gases. These processes involve the conjugate addition of Et2AlI to a,â-unsaturated substrates followed by carbonyl coupling. Releasing CH3CH3 is believed to act as a strong driving force and make the reactions irreversible.

New electrophilic imidazolination reaction of enones was developed using 2-NsNCl2 as the electrophilic nitrogen source without any catalyst. It showed faster reaction rates and higher chemical yields than the reaction using analogous nitrogen source, 4-TsNCl2, under similar conditions. Molecular sieves and temperature played important roles to control the formation of desired products, l-o-nitrobenzenesulfonyl-3-dichloromethyl- 4,5-imidazolines and l-o-nitrobenzenesulfonyl-3-trichloromethyl-4,5-imidazolines. A [2+3] cycloaddition reaction was proposed as one step for the reaction to explain the regio- and stereoselectivity.

a,â-Differentiated 1,2-vicinal diamines have been efficiently synthesized with good to excellent yields (87 - 96%) by using the new electrophilic imidazolination reaction of alkenes. The hydrolysis of imidazolines was performed by treatment with 6 A'' HCl in THF at 70 °C or in CHCI3 at 50 °C without epimerization.