142185-62-4Relevant academic research and scientific papers
Copper(I)-catalyzed borylative exo -cyclization of alkenyl halides containing unactivated double bond
Kubota, Koji,Yamamoto, Eiji,Ito, Hajime
, p. 2635 - 2640 (2013/03/29)
A borylative exo-cyclization of alkenyl halides has been reported. The reaction includes the regioselective addition of a borylcopper(I) intermediate to unactivated terminal alkenes, followed by the intramolecular substitution of the resulting alkylcopper(I) moiety for the halide leaving groups. Experimental and theoretical investigations of the reaction mechanism have also been described. This reaction provides a new method for the synthesis of alkylboronates containing strained cycloalkyl structures from simple starting materials.
Enantioselective cyclopropanation of allylic alcohols with dioxaborolane ligands: Scope and synthetic applications
Charette, André B.,Juteau, Hélène,Lebel, Hélène,Molinaro, Carmela
, p. 11943 - 11952 (2007/10/03)
A very effective chiral controller has been found for the conversion of allylic alcohols into the corresponding enantiomerically enriched cyclopropanes using bis(iodomethyl)zinc. A variety of chiral, nonracemic cyclopropylmethanols could be obtained according to this method. This methodology was extended with success to the cyclopropanation of unconjugated and conjugated polyenes and homoallylic alcohols. The cyclopropanation of allylic carbamates has also been investigated with this system, but it was found that enantioenriched cyclopropylmethylamines are best prepared from enantioenriched cyclopropylmethanols.
A Catalytic Enantioselective Reaction Using a C2-Symmetric Disulfonamide as a Chiral Ligand: Simmons-Smith Cyclopropanation of Allylic Alcohols by the Et2Zn-CH2I2-Disulfonamide System
Takahashi, Hideyo,Yoshioka, Masato,Shibasaki, Masakatsu,Ohno, Masaji,Imai, Nobuyuki,Kobayashi, Susumu
, p. 12013 - 12026 (2007/10/02)
A catalytic and enantioselective Simmons-Smith cyclopropanation of an allylic alcohol was developed by the reaction of an allylic alcohol with Et2Zn and CH2I2 in the presence of a catalytic amount of chiral disulfonamide 4.
Synthesis of Optically Active cis- and trans-1,2-Disubstituted Cyclopropane Derivatives by the Simmons-Smith Reaction of Allyl Alcohol Derivatives Derived from (R)-2,3-O-Isopropylideneglyceraldehyde
Morikawa, Tsutomu,Sasaki, Hirofumi,Hanai, Ryo,Shibuya, Akira,Taguchi, Takeo
, p. 97 - 103 (2007/10/02)
The Simmons-Smith reactions of Z- and E-allyl alcohol derivatives 6 derived from (R)-2,3-O-isopropylideneglyceraldehyde (5) were used for the synthesis of optically active cis- and trans-1,2-disubstituted cyclopropane derivatives.Reaction of 6 with diethyl zinc and diiodomethane gave cyclopropane derivatives 7 in 84percent to quantitative yields with 35 to ca. 100percent des.Identical facial selectivities toward the double bonds, 1re-2si for Z-6 and 1re-2re for E-6, were observed in the cyclopropanations.The diastereoselectivity was dependent on the protecting group on the terminal allylic oxygen (R of 6, TBDPS > MOM > Bn) and on the stereochemistry of the double bond (Z > E).For TBDPS ethers Z- and E-6c, cis- and trans-7c were obtained as single diastereomers, respectively.It was clearly demonstrated that the stereoselectivity of the cyclopropanation is controlled by the directing effect of the allylic oxygen (O-1) of the dioxolane ring, which coordinates to the reagent.The terminal allylic oxygen (O-2) lowered the diastereoselectivity.This reaction was applied to the synthesis of optically active cyclopropane analogs of γ-aminobutyric acid (GABA) 18, 22, and ent-22.
