ChemInform Abstract: Regiodivergent Enantioselective γ‐Additions of Oxazolones to 2,3‐Butadienoates Catalyzed by Phosphines: Synthesis of α,α‐Disubstituted α‐Amino Acids and N,O‐Acetal Derivatives.

Wang, Tianli; Yu, Zhaoyuan; Hoon, Ding Long; Phee, Claire Yan; Lan, Yu; Lü, Yixin

doi:10.1002/chin.201629159

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“…In a further investigation, Lu, Lan, and co-workers achieved regiodivergent C-2-and C-4-selective γ-additions of oxazolones to allenoates (Scheme 140). 215 In the presence of the O-TBDPS-L-threonine-based phosphine P36, when 2-aryl-4alkyloxazol-5-(4H)-ones were employed as pronucleophiles, γaddition to tert-butyl buta-2,3-dienoate led to C-4-selective γaddition providing the major products. A variety of oxazolones with alkyl substituents at the 4-position worked well, giving their desired products in good to excellent yields and stereoselectivities, whereas oxazolones with aryl substituents at the 4-position were unsuitable, giving their products with lower values of ee.…”

Section: Phosphine-catalyzed Isomerization Of Allenes To Dienesmentioning

confidence: 99%

Phosphine Organocatalysis

et al. 2018

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The hallmark of nucleophilic phosphine catalysis is the initial nucleophilic addition of a phosphine to an electrophilic starting material, producing a reactive zwitterionic intermediate, generally under mild conditions. In this Review, we classify nucleophilic phosphine catalysis reactions in terms of their electrophilic components. In the majority of cases, these electrophiles possess carbon–carbon multiple bonds: alkenes (section 2), allenes (section 3), alkynes (section 4), and Morita–Baylis–Hillman (MBH) alcohol derivatives (MBHADs; section 5). Within each of these sections, the reactions are compiled based on the nature of the second starting material—nucleophiles, dinucleophiles, electrophiles, and electrophile–nucleophiles. Nucleophilic phosphine catalysis reactions that occur via the initial addition to starting materials that do not possess carbon–carbon multiple bonds are collated in section 6. Although not catalytic in the phosphine, the formation of ylides through the nucleophilic addition of phosphines to carbon–carbon multiple bond–containing compounds is intimately related to the catalysis and is discussed in section 7. Finally, section 8 compiles miscellaneous topics, including annulations of the Hüisgen zwitterion, phosphine-mediated reductions, iminophosphorane organocatalysis, and catalytic variants of classical phosphine oxide–generating reactions.

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Section: Phosphine-catalyzed Isomerization Of Allenes To Dienesmentioning

confidence: 99%