Towards an asymmetric β-selective addition of azlactones to allenoates

• Behzad Nasiri,
• Ghaffar Pasdar,
• Paul Zebrowski,
• Katharina Röser,
• David Naderer and
• Mario Waser

Beilstein J. Org. Chem. 2024, 20, 1504–1509, doi:10.3762/bjoc.20.134

• in a straightforward manner. Conclusion The development of novel catalytic methods for the asymmetric synthesis of non-natural amino acid derivatives is a contemporary task and we herein introduce an organocatalytic protocol for the β-selective addition of various azlactones 1 to allenoates 3. Upon

(Bio)isosteres of ortho- and meta-substituted benzenes

• H. Erik Diepers and
• Johannes C. L. Walker

Beilstein J. Org. Chem. 2024, 20, 859–890, doi:10.3762/bjoc.20.78

• , respectively (Scheme 12B) [58]. Saponification of the ester moieties in these species followed by Curtius rearrangements then led to amines 114 and 116. Non-natural amino acid derivatives 113 and 117 are intermediates prepared using these methods that could be of interest to medicinal chemistry. Alcohol 111

Transition-metal-catalyzed domino reactions of strained bicyclic alkenes

• Austin Pounder,
• Eric Neufeld,
• Peter Myler and
• William Tam

Beilstein J. Org. Chem. 2023, 19, 487–540, doi:10.3762/bjoc.19.38

• desired carboaminated product in slightly diminished yields while azabicyclic alkenes generated the targeted products in excellent yield, albeit with slightly reduced enantioselectivity. To showcase the synthetic capabilities of this methodology, the authors synthesized the non-natural amino acid

Naphthalene diimide–amino acid conjugates as novel fluorimetric and CD probes for differentiation between ds-DNA and ds-RNA

• Annike Weißenstein,
• Myroslav O. Vysotsky,
• Ivo Piantanida and
• Frank Würthner

Beilstein J. Org. Chem. 2020, 16, 2032–2045, doi:10.3762/bjoc.16.170

• significant Stokes shifts of emission (+60 nm) characterised by good quantum yield in aqueous solution. Thus, NDIs 3a and 3b are novel intensively fluorescent non-natural amino acid probe molecules with both, N- and C-termini available for incorporation into any peptidoid construct requiring a fluorescent tag

Economical and scalable synthesis of 6-amino-2-cyanobenzothiazole

• Jacob R. Hauser,
• Hester A. Beard,
• Mary E. Bayana,
• Katherine E. Jolley,
• Stuart L. Warriner and
• Robin S. Bon

Beilstein J. Org. Chem. 2016, 12, 2019–2025, doi:10.3762/bjoc.12.189

• bioorthogonal reaction (k ≈ 10 M−1s−1) [9] for site-specific labelling or immobilisation of proteins 4, either at an N-terminal cysteine residue or at a 1,2-aminothiol group incorporated into a non-natural amino acid (Scheme 1) [10][11]. In addition, CBT derivatives have been used for the synthesis of polymeric

A new synthetic protocol for coumarin amino acid

• Xinyi Xu,
• Xiaosong Hu and
• Jiangyun Wang

Beilstein J. Org. Chem. 2013, 9, 254–259, doi:10.3762/bjoc.9.30

• and relatively easy to prepare this kind of fluorescent amino acid with the new synthetic method. Furthermore, it can be applied to synthesize other derivatives of the coumarin amino acid with some specific properties. Keywords: coumarin; fluorescent probe; halogen derivatives; non-natural amino acid

• ; Pechmann condensation; Introduction Since α-L-(2-(7-hydroxycoumarin-4-yl)ethyl)glycine (1a, Figure 1), a fluorescent non-natural amino acid, was genetically incorporated at a defined site in proteins in living organisms for the first time by Schultz and co-workers [1] there have been more and more

• be accepted exclusively from the racemic mixture since there is not any report indicating that D-amino acids exist in proteins. A related report proved that in the incorporation of a non-natural amino acid into a protein, the L-enantiomer is accepted exclusively from the racemic mixture [19

Synthesis of the fluorescent amino acid rac-(7-hydroxycoumarin-4-yl)ethylglycine

• Manfred Braun and
• Torsten Dittrich

Beilstein J. Org. Chem. 2010, 6, No. 69, doi:10.3762/bjoc.6.69

• be considered a drawback: However, it has been proven for a related non-natural amino acid [8], that in the incorporation into a protein during translation on the ribosome, the L-enantiomer is accepted exclusively from the racemic mixture. Thus, one can assume that, for in vivo incorporation, the