P(CH<sub>3</sub>NCH<sub>2</sub>CH<sub>2</sub>)<sub>3</sub>N as a Dehydrobromination Reagent: Synthesis of Vitamin A Derivatives Revisited
作者:Andrzej E. Wróblewski、John G. Verkade
DOI:10.1021/jo010648+
日期:2002.1.1
Although P(CH(3)NCH(2)CH(2))(3)N (1) was found to be less effective than 1,5-diazabicyclo[4.3.0]non-5-ene (DBN) or 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) in the removal of hydrogen bromide from vitamin A intermediates 13-cis-10-bromo-9,10-dihydroretinyl acetates (6) and 14-bromo-9,14-dihydroretinyl acetate (11) when the reaction was carried out in refluxing benzene, in acetonitrile at room temperature
Stereocontrolledconvergentsynthesis of vitamin A was achieved by the doubleelimination method employing the C10 sulfone and the C10 aldehydes as starting materials. Thus the all-trans and 13-cis isomers were obtained with the stereochemical purity of 95% and 90%, respectively.
Ionic photodissociation of polyenes via a highly polarized singlet excited state
作者:A. Mahipal Reddy、V. Jayathirtha Rao
DOI:10.1021/jo00051a011
日期:1992.12
Several polyene acetates and polyene methyl ether were prepared. Upon direct excitation these polyenes undergo ionic photodissociation from their singlet excited states. Triplet-sensitization experiments on these polyenes revealed that the ionic photodissociation process is restricted to singlet excited states. The rationale put forward is that the polyene chromophore undergoes charge separation/polarization in the singlet excited state, which leads to ionic photodissociation.
Stereocontrolled synthesis of vitamin A through a double elimination reaction. A novel convergent C10 + C10 route