Diastereoselective Allylation of Carbonyl Compounds and Imines: Application to the Synthesis of Natural Products

Abstract

2.2. Chiral Imines and Imine Derivatives 2.2.1. Imines and Imine Derivatives from Chiral Carbonyl Compounds. Chiral α-oxysubstituted aldehydes were used by Kobayashi and co-workers in a three-component reaction with allylboropinacolate and ammonia in ethanol. The corresponding homoallylic primary amines were obtained with good to high syn diastereofacial selectivities (Scheme 5). 20 The precise reaction mechanism was unclear. Preformation of N-Scheme 3 Scheme 4 Scheme 5 Chemical Reviews Review dx.

Highly Diastereo‐ and Enantioselective Cu‐Catalyzed Borylative Coupling of 1,3‐Dienes and Aldimines

“…Branched homoallylic amines are readily prepared in as yn-selective manner with high regio-, diastereo-and enantioselectivity.M oreover,t hese three-component coupling reactions feature good functional-group compatibility and easy access to the substrates and catalyst.Asymmetric allylation reactions [1] of imines have received increasing interests from the synthesis community [2] because enantioenriched homoallylic amine products are useful building blocks in organic synthesis and medicinal chemistry.[3] Copper catalysis is an efficient approach to promote the enantioselective addition of terminal allyl transmetalation reagents (e.g., with B, Si, and Sn) to imines, [4] however,C ucatalyzed asymmetric, nucleophilic addition to imines with functionalized (e.g., g-substituted) allyl metal reagents remain challenging.T his is probably due to inefficiencyo f the transmetalation event arising from increased steric hindrance,t he weak electrophilicity/reactivity of imines, and/or difficulties in predicting the regio-and stereochemical outcome of additions.N ew and efficient approaches to generating and utilizing functionalized allyl metal reagents in the presence of acopper catalyst hold promise for accessing complex homoallylic amines,a nd these methods will expand the application of catalytic asymmetric allylation chemistry.Since the seminal work of borylcopper catalysis reported by the Ito [5] and the Miyaura [6] groups,C u-catalyzed borylative coupling reactions have been recognized as an important method for generating boron-containing organocopper species in situ from an unsaturated hydrocarbon. [7] In this context, Hoveyda pioneered the use of boron-functional allylcopper intermediates in enantioselective allylation of aldehydes/ketones, [7f] allyllic esters, [7i] and enoates.…”

“…Asymmetric allylation reactions [1] of imines have received increasing interests from the synthesis community [2] because enantioenriched homoallylic amine products are useful building blocks in organic synthesis and medicinal chemistry.…”

“…Asymmetric allylation reactions [1] of imines have received increasing interests from the synthesis community [2] because enantioenriched homoallylic amine products are useful building blocks in organic synthesis and medicinal chemistry. [3] Copper catalysis is an efficient approach to promote the enantioselective addition of terminal allyl transmetalation reagents (e.g., with B, Si, and Sn) to imines, [4] however,C ucatalyzed asymmetric, nucleophilic addition to imines with functionalized (e.g., g-substituted) allyl metal reagents remain challenging.T his is probably due to inefficiencyo f the transmetalation event arising from increased steric hindrance,t he weak electrophilicity/reactivity of imines, and/or difficulties in predicting the regio-and stereochemical outcome of additions.N ew and efficient approaches to generating and utilizing functionalized allyl metal reagents in the presence of acopper catalyst hold promise for accessing complex homoallylic amines,a nd these methods will expand the application of catalytic asymmetric allylation chemistry.…”

Gold‐Catalyzed Imination/Mannich Reaction Cascades of 3‐En‐1‐ynamides with Anilines and Aldehydes to Enable 1,5‐Nitrogen Functionalizations

“…[8] Generationo fr eactive allylgold species from the aminations of 3-en-1-ynamides assists the design of new catalytic reactions because the resulting a-imino allylgold species can be trapped with imines without aprotodeauration reaction.…”

Catalytic Enantioselective Assembly of Homoallylic Alcohols from Dienes, Aryldiazonium Salts, and Aldehydes

“…[1] As such, the creation of new synthetic methods to access these molecules has long and continuously received widespread attention. [2][3][4] Traditionally, the most reliable methods rely on the stereoselective addition of allylic metal reagents to carbonyl groups,asdemonstrated by many well-known and widely applicable reactions.…”