100281-14-9Relevant articles and documents
Chiral Synthesis via Organoboranes. 44. Racemic and Diastereo- and Enantioselective Homoallenylboration Using Dialkyl 2,3-Butadien-1-ylboronate Reagents. Another Novel Application of the Tandem Homologation-Allylboration Strategy
Ramachandran, P. Veeraraghavan,Li, Guisheng,Brown, Herbert C.
, p. 100 - 104 (1996)
A highly general and efficient racemic and diastereo- and enantioselective homoallenylboration has been achieved with a novel boron reagent, dialkyl 2,3-butadien-1-ylboronate (dialkyl homoallenylboronate).The starting isopropyl 2,3-butadien-1-ylboronate is prepared from allenylmagnesium bromide and diisopropyl (halomethyl)boronate.This β,γ-unsaturated boronate reagent reacts readily with aldehydes via usual allylic rearrangement to give the alkyl(1,3-butadien-2-yl)methanols in excellent yields.Among the solvents examined, toluene favored enhanced reaction rates.The reaction is relatively sensitive to steric effects, so that sterically hindered aldehydes react significantly slower.Generaly, the reactivities are moderately lower than those of the corresponding simple allylboronates, possibly due to the reduced HOMO electron density of the internal double bond.Also, the reagent exhibits a unique anti diastereoselectivity in reaction with α-chiral aldehydes in contrast to the syn selectivity observed with a corresponding organosilicon reagent.However, this anti selectivity is similar to that observed for the allylboration reactions.We have successfully extended this reaction to the first general synthesis of optically active alkyl(1,3-butadien-2-yl)methanol using chiral tartrate boronate reagents with diisopropyl tartrate (DIPT) and bis(2,4-dimethyl-3-pentyl) tartrate (DMPT) as the chiral modifiers.These reagents react with aldehydes even at -78 deg C, albeit slowly, and exhibit remarkable enantioselectivity with al classes of aldehydes examined with the exception of aromatic and α-alkoxy aldehydes.Again, while the selectivity parallels that of the corresponding allylboronate, the reactivities are lower.Also, the double asymmetric homoallenylboronation of 2,3-O-isopropylidene-D-glyceraldehyde using the DMPT modified boronate reagent gives an excellent 98.5percent anti selectivity in the matched case and a moderately lower value, 82percent syn selectivity, in the mismatched case.
Racemic and diastereoselective synthesis of alkyl(1,3-butadien-2-yl) methanols via a novel homoallenylboration of aldehydes with diisopropyl 2,3-butadien-1-ylboronate
Brown, Herbert C.
, p. 2441 - 2444 (1995)
Diisopropyl 2,3-butadien-1-ylboronate has been prepared by a simple method and its utility as a novel homoallenylborating reagent has been demonstrated with a series of aldehydes. Also, a high diastereoselectivity of this reagent in its reaction with an α
First regio- and enantioselective chromium-catalyzed homoallenylation of aldehydes
Coeffard, Vincent,Aylward, Miriam,Guiry, Patrick J.
supporting information; experimental part, p. 9152 - 9155 (2010/03/03)
Game, set, and match: The first regio- and enantioselective version of the title reaction is described. The chiral catalyst prepared in situ from CrCl 3 and a non-C2-symmetric bis(oxazoline) ligand 1 affords the valuable chiral ss-al
Regioselective buta-1,3-dienylation of aldehydes via transmetallation of 2-tributylstannylbuta-1,3-diene
Luo, Meiming,Iwabuchi, Yoshiharu,Hatakeyama, Susumi
, p. 1109 - 1111 (2007/10/03)
Transmetallation of 2-tributylstannylbuta-1,3-diene with SnCl4 followed by Lewis base promoted addition of the resulting 1-trichlorostannyl-2,3-butadiene to aldehydes in the presence of DMF allows their buta-1,3-dienylation to take place at the
