Highly Selective Allylborations of Aldehydes Using α,α‐Disubstituted Allylic Pinacol Boronic Esters

Hesse, M.; Essafi, Stéphanie; Watson, Charlotte G.; Harvey, Jeremy N.; Hirst, David; Willis, Christine L.; Aggarwal, Varinder K.

doi:10.1002/anie.201402995

Cited by 64 publications

(23 citation statements)

References 89 publications

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“…The R absolute configuration of 3a was determined by comparing its optical rotation with reported data. 14 b Isolated yields. c Determined by HPLC on a chiral IC-3 column.…”

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confidence: 99%

“…The R absolute configuration of 3a was determined by comparing its optical rotation with reported data. 14 …”

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confidence: 99%

“…For example, Aggarwal reported a stereospecific allylation between the diboronic ester ( S )- 3a and benzaldehyde to form a tetrasubstituted alkene after a Suzuki–Miyaura cross-coupling. 14 , 18 , 9k To further explore the synthetic applications of such chiral diboronic esters, an enantioselective synthesis of brassinazole, 19 a specific inhibitor of brassinosteroid biosynthesis, was studied with ( R )- 3a as the starting material ( Scheme 1 ). Surprisingly, despite its significant biological properties, its enantioselective synthesis had not been reported to our knowledge.…”

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Enantioselective palladium-catalyzed diboration of 1,1-disubstituted allenes

et al. 2017

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“…The R absolute configuration of 3a was determined by comparing its optical rotation with reported data. 14 b Isolated yields. c Determined by HPLC on a chiral IC-3 column.…”

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confidence: 99%

“…The R absolute configuration of 3a was determined by comparing its optical rotation with reported data. 14 …”

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confidence: 99%

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confidence: 99%

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Enantioselective palladium-catalyzed diboration of 1,1-disubstituted allenes

et al. 2017

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“…Aggarwal and co-workers have investigated the chelation-assisted substrate-controlled (CASC), asymmetric lithiation, and allylboration through less-sterically demanding chiral carbamates and explored its application for selectively making C-C bonds [9,10,11,12,13,14,15,16,17,18]. Previously, we have described this methodology to obtain highly selective products through substituted boranes ( trans -alkenyl-9-BBN) and boronic esters and their reactions with sparteine-complexed lithiated carbamates [19].…”

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Chelation-Assisted Substrate-Controlled Asymmetric Lithiation-Allylboration of Chiral Carbamate 1,2,4-Butanetriol Acetonide

et al. 2015

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Abstract:The lithiation of 2-(2,2-dimethyl-1,3-dioxolan-4-yl)ethyl diisopropylcarbamate (1) is achieved freely by sec-butyllithium in diethylether with high lk-diastereoselectivity: the bicyclic chelate complexes 3a and 3b are reacted with electrophiles to form optically active precursors 4a and 4b with >95% diastereoselectivity. In addition, tertiary diamines can undergo an external complexation in contest with the internal oxygen ligand, leading to improved stereoselectivities. The further reactions of lithiated carbamates with trans alkenyl-9-BBN derivatives after 1,2 metallate rearrangements, gave the key intermediate α-substituted allylic boranes 7. Subsequent allylboration of aldehydes gave (Z)-anti-homoallylic alcohols 8 in good yield and excellent d.r.

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“…[16] By contrast, the 4-boryl-4-dihydropyridine products described here are unknown reagents.Therefore we next explored their synthetic utility.For example,addition of the allyl boronate to benzaldehyde generated the desired homoallylic alcohol (AE)-52 with good yield and diastereoselectivity (Scheme 3a). [17] Hydrogenation of (AE)-52 gave the trisubstituted piperidine (AE)-53 while oxidation provided the disubstituted pyridine 54, …”

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confidence: 99%