Methods for direct generation of α-alkyl-substituted aldehydes

Efficient Access to All‐Carbon Quaternary and Tertiary α‐Functionalized Homoallyl‐type Aldehydes from Ketones

“…[1] From ar eactivity perspective,t he high electrophilicity of the aldehyde moiety represents an excellent tool for constructing sterically hindered quaternary centers.I nt his context, the a-allylation of aldehydes to generate the corresponding homoallyl derivatives has been extensively investigated (Scheme 1A1). [8] Amajor advancement in the field was reported in 2016 by Evans and Wright, who developed an enantioselective rhodium-catalyzed allylation of prochiral a,a-disubstituted aldehyde enolates with allyl benzoate (Scheme 1A2). [2] Fine-tuning of the reaction conditions enabled the development of highly enantioselective variants by the groups of List [3] and Yoshida, [4] which complement asymmetric organocatalytic (Jacobsen) [5] and stereodivergent dual-catalytic (Carreira) [6] approaches.T he process also benefits from switching to nickel catalysis,a sr ecently disclosed by Sauthier and coworkers.…”

Cooperative Catalysis: Enantioselective Propargylic Alkylation of Propargylic Alcohols with Enecarbamates Using Ruthenium/Phosphoramide Hybrid Catalysts

“…In particular, the development of reactions undergoing cooperative catalysis using transition-metal catalysts and organocatalysts has opened up new fields in organic synthesis. [2,3] Many such reactions have been achieved by simple mixing of two distinct catalysts as shown in Scheme 1 a.To develop a new type of cooperative catalysis, we envisaged the use of hybrid catalysts derived from both transition-metal catalysts and organocatalysts within the same molecule (Scheme 1 b). The use of such hybrid catalysts may increase the reactivity and enantioselectivity of the reactions.…”

“…Typical results are shown in Table 2. A high enantioselectivity was observed when substituents such as methyl, methoxy, and chloro groups were introduced at the paraposition of the benzene ring of propargylic alcohols (entries [2][3][4]. The position of the methyl group on the benzene ring affected the enantioselectivity.…”

Cooperative Catalysis: Enantioselective Propargylic Alkylation of Propargylic Alcohols with Enecarbamates Using Ruthenium/Phosphoramide Hybrid Catalysts

“…In particular, the development of reactions undergoing cooperative catalysis using transition-metal catalysts and organocatalysts has opened up new fields in organic synthesis. [2,3] Many such reactions have been achieved by simple mixing of two distinct catalysts as shown in Scheme 1 a.…”

“…Typical results are shown in Table 2. A high enantioselectivity was observed when substituents such as methyl, methoxy, and chloro groups were introduced at the paraposition of the benzene ring of propargylic alcohols (entries [2][3][4]. The position of the methyl group on the benzene ring affected the enantioselectivity.…”