Diastereoselectivity of Additions to Chiral Carbonyl Oxides
摘要:
The influence of a resident stereocenter on the formation of hydroperoxy acetals from carbonyl oxides is investigated. Addition of either methanol or 2-propanol to 8-phenylpropanal O-oxide proceeds with modest stereoselectivity; addition of a tertiary alcohol proceeds with higher selectivity. Product stereochemistry, which is confirmed by conversion of a functionalized hydroperoxy acetal to a 1,2-dioxane, is found to derive from nucleophilic attack through a Felkin-Anh type transition state. Trapping of a carbonyl oxide containing a neighboring hydrogen bond donor proceeds with modest selectivity for both syn- and anti-carbonyl oxide isomers. Ozonolysis of a 3-(trialkylstannyl)-1-enol ether proceeds with loss of the stannyl-bearing carbon through the possible intermediacy of a vinyl peroxide.
Diastereoselectivity of Additions to Chiral Carbonyl Oxides
作者:Patrick H. Dussault、Umesh R. Zope
DOI:10.1021/jo00130a021
日期:1995.12
The influence of a resident stereocenter on the formation of hydroperoxy acetals from carbonyl oxides is investigated. Addition of either methanol or 2-propanol to 8-phenylpropanal O-oxide proceeds with modest stereoselectivity; addition of a tertiary alcohol proceeds with higher selectivity. Product stereochemistry, which is confirmed by conversion of a functionalized hydroperoxy acetal to a 1,2-dioxane, is found to derive from nucleophilic attack through a Felkin-Anh type transition state. Trapping of a carbonyl oxide containing a neighboring hydrogen bond donor proceeds with modest selectivity for both syn- and anti-carbonyl oxide isomers. Ozonolysis of a 3-(trialkylstannyl)-1-enol ether proceeds with loss of the stannyl-bearing carbon through the possible intermediacy of a vinyl peroxide.
Stereoselective addition of phenyl selenyl chloride to methoxy alkenes derived from N-protected chiral α-amino acids.
作者:Mariangela Demarcus、Silvia N. Filigheddu、André Mann、Maurizio Taddei
DOI:10.1016/s0040-4039(99)00761-3
日期:1999.6
(E)-Methoxy alkenes derivedfrom N-Boc or N-Cbz α-amino acids undergo stereoselectiveaddition of phenyl selenyl chloride in the presence of Ti(Oi-Pr)4 and LiCl to give the corresponding phenylselenyl aldehydes that can be easily transformed into new enantiomerically pure amino acids containing an aziridine ring.
衍生自N-Boc或N-Cbzα-氨基酸的(E)-甲氧基烯烃在Ti(O i -Pr)4和LiCl的存在下进行立体选择性加成的苯基硒基氯,得到相应的苯基硒基醛,可以很容易地转化为含有氮丙啶环的新对映体纯氨基酸。