- Inter- and intramolecular pathways for the formation of tetrahydrofurans from β-(phosphatoxy)alkyl radicals. Evidence for a dissociative mechanism
-
β-(Phosphatoxy)alkyl radicals generated by photolysis of Barton PTOC esters in the presence of allyl alcohol and tert-butyl mercaptan undergo nucleophilic substitution followed by 5-exo-trig radical ring closure leading to tetrahydrofurans in good yield and with high trans selectivity. β- (Phosphatoxy)alkyl radicals obtained by intramolecular hydrogen 1,5- abstraction with an alkoxyl radical undergo nucleophilic displacement providing tetrahydrofurans. The ensemble of results, including the effects of leaving groups and substituents, strongly support a dissociative mechanism for these radical nucleophilic displacement reactions.
- Crich, David,Huang, Xianhai,Newcomb, Martin
-
p. 523 - 529
(2007/10/03)
-
- Arene-catalysed reductive lithiation of tetrahydrofuran: Improved synthesis of 1,5-diols
-
The reductive cleavage of tetrahydrofuran at -78°C can be easily achieved by using an excess of lithium powder in the presence of BF3-·OEt2 and a catalytic amount (8%) of an arene (naphthalene, biphenyl, 4,4'-di-tert-butylbiphenyl or anthracene), the best results being obtained with naphthalene. The dianion prepared by this method reacts with carbonyl compounds yielding 1,5-diols.
- Ramon,Yus
-
p. 3585 - 3588
(2007/10/02)
-