Electrolytic Partial Fluorination of Organic Compounds. 17. Regiospecific Anodic Fluorination of Sulfides Bearing Electron-Withdrawing Substituents at the Position .alpha. to the Sulfur Atom
摘要:
Regiospecific monofluorination of various sulfides bearing electron-withdrawing substituents, cyano, ester, acyl, amino, and phosphonate groups,at their alpha-positions was successfully carried out by the anodic oxidation of the sulfides in Et(3)N . 3HF/MeCN using an undivided cell. Fluorine was introduced at the position alpha to the sulfur atom selectively. Fluorination of alpha-(phenylthio)-substituted cyclic carbonyl compounds was also successful. Furthermore, anodic alpha,alpha-difluorination of ethyl alpha-(phenylthio)acetate was also successfully carried out although a large amount of electricity was required.
Facile stereoselective synthesis of cis- and trans-3-alkoxyazetidin-2-ones
作者:Aman Bhalla、Paloth Venugopalan、Shamsher S. Bari
DOI:10.1016/j.tet.2006.06.062
日期:2006.8
A highly stereoselectivesynthesis of cis- and trans-3-alkoxy-3-phenyl/benzylthioazetidin-2-ones is described. The reaction of α-chlorosulfide-β-lactams with various alcohols catalyzed by a Lewis acid such as ZnCl2 in the presence of molecular sieves (3–4 Å) leads to cis-3-alkoxy-3-phenyl/benzylthio-β-lactams whereas treatment of potassium 2-alkoxy-2-phenylthioethanoate with appropriate Schiff's base
Chemoenzymatic Approaches to the Montanine Alkaloids: A Total Synthesis of (+)-Brunsvigine
作者:Martin G. Banwell、Okanya J. Kokas、Anthony C. Willis
DOI:10.1021/ol071344y
日期:2007.8.1
available and enzymatically derived cis-1,2-dihydrocatechols 3a and 3b have been elaborated over 17 steps, including a novel radical addition/elimination sequence, into the enantiomer, (+)-1, of the montanine alkaloid brunsvigine [(-)-1].
Synthesis of oxacyclic carboxylic esters through ring closure of α-alkoxy ester free radicals
作者:Lucie D.M. Lolkema、Henk Hiemstra、Al Ayachi Al Ghouch、W. Nico Speckamp
DOI:10.1016/0040-4039(91)80366-e
日期:1991.3
Cyclizations of 1-methyoxycarbonyl-2-oxa-5-hexenyl (and related) radical intermediates, generated from phenylthio precursors, proceed in good yields and mainly lead to substituted 2-tetrahydrofurancarboxylic esters.
Chloromethyl phenyl sulfides 3 underwent [4+ +2] type polar cyclo-additions with styrene, trans-stilbene, and phenylacetylene in the presence of stannicchloride to afford the thiochroman 4, 5 and thiochromen derivatives 6. Under the same reaction conditions, N-allyl-α-chloro-α-(phenylthio)acetamide (7) gave the intramolecular cycloaddition product 8.