87640-84-4Relevant articles and documents
(E)-1-(Phenylsulfonyl)-4-(trimethylsilyl)-1-butene: An Advantageous Synthetic Equivalent for the 1-(1,3-Butadienyl) Anion and the 1,1-(1,3-Butadienyl) Dianion
Meagher, Timothy P.,Shechter, Harold
, p. 4193 - 4198 (2007/10/03)
The (E)-1-(arylsulfonyl)-4-(trimethylsilyl)-1-butenes 9, 25, and 26 are prepared by CuCl2-promoted and by photolytic additions of their precursor 1-arylsulfonyl chlorides and bromides to 4-(trimethylsilyl)-1-butene (14) and then dehydrohalogenation of the resulting 1-(arylsulfonyl)-2-halo-4-(trimethylsilyl)butanes 15a, 15b, 23a, and 23b with KOH, LDA, or n-BuLi. Silylbutene 14 is obtained from reaction of [(trimethylsilyl)methyl]magnesium chloride (16, X = Cl) and allyl bromide (17) and better by protiodesilylations of (E)- and (Z)-1,4-bis(trimethylsilyl)-2-butenes (20) with sulfuric or trifluoroacetic acids. (Arylsulfonyl)(trimethylsilyl)-1-butenes 9, 25, and 26 are converted efficiently by LDA or n-BuLi at -78°C to 1-(arylsulfonyl)-1-lithio-4-(trimethylsilyl)-1-butenes 10, 27a, and 27b, respectively. Reactions of 27a and 27b with deuterium oxide yield (E)-1-(4-chlorophenylsulfonyl)-1-deuterio-4-(trimethylsilyl)-1-butene (28a, 83%) and (E)-1-deuterio-1-(4-methylphenylsulfonyl)-4-(trimethylsilyl)-1-butene (28b, 89%), respectively. 1-Lithio derivatives 10, 27a, and 27b undergo benzylations by benzyl bromide in THF/HMPA with retention of the positions of their olefinic double bonds to give the (E)-2-(arylsulfonyl)-1-phenyl-5-(trimethylsilyl)-2-pentenes 29a, 29b, and 29c, respectively, in 84-90% yields. Of particular interest is that 29a-c are isomerized to their corresponding 2-(arylsulfonyl)-1-phenyl-5-(trimethylsilyl)-3-pentenes 30a-c, respectively, which then undergo conjugative eliminations of their arylsulfonyl and their trimethylsilyl groups to give (E)-5-phenyl-1,3-pentadiene (33) in 56-63% yields upon reactions with TBAF in THF at 25°C. Further, 27b reacts with 1,3-dichloropropane to form 1-chloro-4-(4-methylphenylsulfonyl)-7-(trimethylsilyl)-4-heptene (35) which is cyclized by n-BuLi to 1-(4-methylphenylsulfonyl)-1-(3-(trimethylsilyl)-1-propenyl)cyclobutane (37, 67%). Elimination of 37 by TBAF then gives allylenecyclobutane (34, n = 3, 84%) simply. This study thus reveals that 9, 25, and 26 have outstanding potential as 1-(1,3-butadienyl) anion (7) and 1,1-(1,3-butadienyl) dianion (8) synthons.
A VINYL SULFONE-MEDIATED DIELS-ALDER APPROACH TO THE FULLY REGIOCONTROLLED ELABORATION OF 4,5-DISUBSTITUTED 2- AND 3-CYCLOHEXENONES
Paquette, Leo A.,Kinney, William A.
, p. 5127 - 5130 (2007/10/02)
Reported here is a scheme which enables one to prepare independently 4,5-disubstituted 2- or 3-cyclohexenones where the nature of the pendant sidechains can be widely varied.
