Esters allylboronic

Addition of Allylboronate Ester 176 to Representative Aldehydes (eq. [116]) (132a)... 

The correlation between allylboronic ester stereochemistry and aldehyde diastereoface selection stands in contrast to the behavior of stereochemicaUy defined lithium enolates, which generally exhibit a preference for the Cram mode of addition to chiral aldehydes from either enolate geometry (cf, eqs. [72]-[77]). The stereochemical... 

The reaction of 2-(l-alkyl-2-alkenyl)-l,3,2-dioxaborolancs with a suitably chosen aldehyde resulting in further C—C bond formation with chirality transfer is described in Section D.1.3.3.3.3. A number of analogous reactions of chiral allylboronic esters with aldehydes are described there as well. 

Allylboron compounds, synthesis, 9, 170-171 5-Allylboron compounds, cross-coupling reactions, 9, 212 Allylboronic esters, synthesis, 9, 194—195 Allyl boryl ethers, isomerization, 10, 88 Allylchlorodimethylsilanes, for carbonyl allylations,... 

Hoffmann, R. W., Herold, T. Enantioselective synthesis of homoallyl alcohols via chiral allylboronic esters. Angew. Chem. Int. Ed. 1978,17, 768-769. 

Table 18 Cram Selectivity in the Addition of Allylboronate Esters to 2,3-0-Isopropylidine-D-glyceraldehyde...

Isomerization. Cationic iridium complex effects selective isomerization of unsymmetrical diallyl ethers and conjugated boronates containing an allylic ether group, including an access to 7-(siloxy)allylboronic esters. The conversion of allyl homoallyl ethers to -y,8-unsaturated carbonyl compounds is promoted by [(cod)IrCl]2. 

Cyclic allylboronate esters of diols can be obtained by reactions of appropriate diols or polyols (e.g. sugars) with activated triethylborane, or by photochemical combination of a trialkylborane with two equivalents of a secondary alcohol (Scheme 18). Conversion of alkenylboron compounds into alkenylmercury been extended to include allenyl and conjugated dienyl... 

The prqraration of rm-BuB(OMe)3 and reit-Bu BOMe have been described in good yield by a one-pot synthesis from BfONfe), and rm-butyllithium. In situ generated (a-haloallyl)lithi-um has been used for the synthesis of o-vinylboronate esters, RCH(CH CH2)B(OR )2, which were readily isomerised to the correspmiding allylboronate esters, RCH CH2B(OR )2 cataly-... 

Jarvo et al. have reported the use of isolated NHCP palladium allyl complexes of the type [(R-2)Pd(i -C3H5)]X (X = C1, OAc, BF ) as catalysts for nucleophihc allylation reactions. They investigated a series of electron-rich monodentate and bidentate ligands (bisphosphines, functionahzed NHCs, monodentate NHCs) for their ability to promote nucleophilic attack of the corresponding palladium allyl complexes on electrophiles in, for example, the conjugate addition of allylboronic esters to a variety of ,p-unsaturated Af-acylpyrroles [15a] as well as the allylation of aldehydes by allylstannanes (Scheme 10.4) [15b]. 

Scheme 10.4 Allylation of a,p-unsaturated W-acylpyrroles and aldehydes with allylboronic esters and allylstannanes catalyzed by an NHCP palladium allyl complex.

Highly substituted enantiomerically pure allylboronic esters have been synthesized and added to aldehydes to give R-configured homoallylic alcohols exclusively. ... 

A [3,3]-sigmatropic cyanate-isocyanate rearrangement has been identified as a route to a-isocyanato allylboronic esters that can be trapped with nucleophiles (Scheme 2). A DFT (density functional theory) investigation of [3,3]-sigmatropic rearrangement versus a [2 4-2]-cycloaddition of a formal 5 2 substitution of imido metal complexes with allylic electrophiles has been reported (Scheme 3). ... 

Diboration of 1,3-Dienes, Allenes, Enones, and Other Unsaturated Molecules. As described previously in the original article, the Pt[0] catalyzed addition of 1,3-dienes with B2pin2 affords various allylboronic esters (eq 4). Reactions using phosphine-based catalysts such as Pt(PPh3)4 stereoselectively produce els -1,4-addition products with Z-configuration for aliphatic and cyclic dienes. The reaction mechanism suggests... 

---