Stereoselective allylboration using (B)-γ-alkoxyallyldiisopinocampheylboranes: highly selective reactions for organic synthesis

Abstract

This review describes the synthesis of novel alkoxyallylborane reagents derived from α-pinene and their applications in stereoselective total synthesis of natural products. These reagents can be conveniently prepared and react readily with a wide variety of aldehydes and imines to provide the corresponding α-alkoxy substituted homoallylic alcohols/amines respectively. The (Z)-γ-alkoxyallylborane reagents provide 1,2-syn α-alkoxy homoallylic alcohols/amines while the corresponding (E)-γ-alkoxyallylborane reagents furnish 1,2-anti products exclusively in very high enantioselectivities.

17O NMR studies of boronic acids and their derivatives

“…The increase in the interest in this class of molecules stems from their application in organic synthesis (e.g. in Suzuki or Chan-Lam couplings, [1][2][3][4][5][6] Miyaura borylation, 7,8 asymmetric reduction and hydroboration [9][10][11][12][13][14][15][16] or Petasis reaction 17,18 ), analytical chemistry (resolving and sensing of diols, sugars and hydroxy acids, biomolecule labeling), [19][20][21][22][23][24][25][26][27][28][29][30][31] pharmacology (as antimicrobial, antiviral or anticancer agents), [32][33][34][35] in medicine for neutron capture therapy of cancer [36][37][38] and in materials science (e.g. for synthesis of porous organic supramolecular networks).…”

Integrated Batch and Continuous Flow Process for the Synthesis of Goniothalamin

“…Allylboranes and boronates derived from α-pinene or diisopropyl tartrates as chiral auxiliaries have been utilized for the enantio- and diastereoselective formation of homoallylic alcohols . Amongst the many reported methods for asymmetric allylation, we chose to investigate these organoborane compounds in this context, in view of their straightforward preparation employing readily available starting materials and because of our continuing interest in exploring the utility of flow chemistry for organometallic synthesis.…”

“…Amongst the many reported methods for asymmetric allylation, we chose to investigate these organoborane compounds in this context, in view of their straightforward preparation employing readily available starting materials and because of our continuing interest in exploring the utility of flow chemistry for organometallic synthesis. Moreover, high enantiomeric excess is usually obtained when performing asymmetric allylation using this approach . Based on this, both Brown (allylborane) and Roush (allylboronates) reagents were prepared and initially evaluated in batch for the asymmetric allylation of trans -cinnamaldehyde ( 10 ) (Tables S1 and S2 in the SI).…”

Highly Functionalized tertiary-Carbinols and Carbinamines from the Asymmetric γ-Alkoxyallylboration of Ketones and Ketimines with the Borabicyclodecanes

“…The utility of γ-alkoxyallylboranes in this regard, first demonstrated to be both diastereo- and regioselective by Hoffmann in 1981, was upgraded to a highly asymmetric conversion by Brown in 1988 with his diisopino­campheyl­borane [B(Ipc) 2 ] reagents . Many notable applications of this method have been forthcoming, including the cytotoxic agents, peloruside A by De Brabander and palmerolide A by Nicolaou to mention only two . Aldimines are also useful substrates for these reagents .…”

“…3 Many notable applications of this method have been forthcoming, including the cytotoxic agents, peloruside A by De Brabander 4 and palmerolide A by Nicolaou 5 to mention only two. 6 Aldimines are also useful substrates for these reagents. 7 Early on, it was recognized that the B(Ipc) 2 -based reagents were ineffective for the allylboration of ketones or ketimines.…”