Asymmetric organocatalytic synthesis of chiral homoallylic amines

• Nikolay S. Kondratyev and
• Andrei V. Malkov

Beilstein J. Org. Chem. 2024, 20, 2349–2377, doi:10.3762/bjoc.20.201

• diaziridine 110 with 88% ee albeit with a modest 42% yield. Overall, this is an interesting example of dearomative allylation of Ν-acylquinolinium salts, though enantioselectivity currently is too low to ensure wider practical application of the method. Enantioselective 2-aza-Cope rearrangement In 2008, a

• conceptually different methodology was reported by Rueping and co-workers [41] that was based on the aza-Cope rearrangement of in situ-formed N-α,α’-diphenyl-(α’’-allyl)methyliminium cations catalysed by the BINOL-derived chiral phosphoric acid 112 (Scheme 23). The amine 113 acting as the allyl donor source

• slightly more efficient with electron-poor substrates. On the other hand, high enantioselectivity was maintained over the aldehyde scope regardless of steric size and position of the substituents. A few years later, Wulff and co-workers [42] further elaborated the aza-Cope rearrangement methodology by

Direct C(sp³)–H allylation of 2-alkylpyridines with Morita–Baylis–Hillman carbonates via a tandem nucleophilic substitution/aza-Cope rearrangement

• Siyu Wang,
• Lianyou Zheng,
• Shutao Wang,
• Shulin Ning,
• Zhuoqi Zhang and
• Jinbao Xiang

Beilstein J. Org. Chem. 2021, 17, 2505–2510, doi:10.3762/bjoc.17.167

• (sp3)–H allylic alkylation of 2-alkylpyridines with Morita–Baylis–Hillman (MBH) carbonates is described. A plausible mechanism of the reaction might involve a tandem SN2’ type nucleophilic substitution followed by an aza-Cope rearrangement. Various alkyl substituents on 2-alkylpyridines were tolerated

• in the reaction to give the allylation products in 26–91% yields. The developed method provides a straightforward and operational simple strategy for the allylic functionalization of 2-alkypyridine derivatives. Keywords: 2-alkylpyridines; allylic alkylation; aza-Cope rearrangement; catalyst-free

• MBH-derived allyl bromides (Scheme 1d) [30]. This reaction was assumed to involve the deprotonation of the initially formed 2-methylpyridinium salt by base to generate an N-allyl enamine intermediate, which undergoes a 3-aza-Cope rearrangement to give the allyl-substituted products. To the best of our

Indium-mediated allylation in carbohydrate synthesis: A short and efficient approach towards higher 2-acetamido-2-deoxy sugars

• Christopher Albler,
• Ralph Hollaus,
• Hanspeter Kählig and
• Walther Schmid

Beilstein J. Org. Chem. 2014, 10, 2230–2234, doi:10.3762/bjoc.10.231

• -Cope rearrangement of N-galactosyl-N-homoallylamines [18]. Aminooctoses, on the other hand, are present in the aminoglycoside antibiotic apramycin [19], in the form of an aminooctodiose derivative. However, only few syntheses of this dipyranoid aminosugar [20][21] were reported so far. Thus, we were

• Kirschenlohr [16] for the synthesis of aminohexoses, proved to be straightforward, albeit the reproducibility and yield usually suffered from the formation of multiple side products [17]. Another interesting approach for the synthesis of higher aminosugars, published by Kunz and Deloisy, consists of an aza