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Abstract The asymmetric access to unreported trans 4-quinolinoxy oxaproline precursors is investigated here in a comparative way by 1,3-dipolar cycloaddition of vinyloxy quinolines with chiral α-alkoxycarbonyl aldonitrones and chiral cyclic surrogates. Graphical abstract Image 1 [ABSTRACT FROM AUTHOR]

A biocrude was obtained via the catalytic hydrothermal treatment of lignocellulosic biomass. This was further co-hydroprocessed with Straight Run Gas Oil (SRGO) under desulphurization conditions. Amounts of biocrude of up to 20 wt% could be co-processed, while maintaining a diesel stream density within the specifications contained in the road diesel regulation EN 590. The changes in the diesel properties associated with an increasing amount of biocrude were not a simple linear function of biocrude content. Rather, some positive correlations seem to exist between biocrude and SRGO at low biocrude contents, possibly due to intramolecular hydrogen transfer, yielding a diesel stream with a better quality than would be obtained from simply mixing hydrotreated pure streams in a 80% to 20% ratio. [ABSTRACT FROM AUTHOR]

1,3-Dipolar cycloadditions of nitrones with pentafluorosulfanyl-substituted acrylic ester and amides afforded new trisubstituted pentafluorosulfanylated isoxazolidines in moderate yields as 4-SF 5 -regioisomers. Theoretical calculations were carried out and the regioselectivity could be explained by the fact that the 5-SF 5 -regioisomer probably undertook a spontaneous degradation in the reaction medium via the loss of pentafluorosulfanyl anion. Diastereoselectivity of the 1,3-dipolar cycloadditions was also assessed according to NMR and X-ray diffraction analysis. [ABSTRACT FROM AUTHOR]

Abstract: A new family of analogs of steganacin, an important antimitotic compound, was accessed. It takes advantage of a completely stereoselective sequence of two key steps. The central dihydropyrane core is built by a highly diastereoselective and facially controlled hetero-Diels–Alder reaction. It is followed by a nonphenolic biaryl oxidative coupling with a complete atropo-stereoselectivity. It leads to a quick way to form cyclic biaryl lignans. [Copyright &y& Elsevier]

Copper-catalyzed vinylation of 2- and 4-hydroxy pyridine and quinoline affords exclusively N- vinylation products. However, vinyl ethers of 4-hydroxy pyridine and quinoline can be prepared via a three-step sequence involving copper-catalyzed C-O cross coupling reaction of the corresponding N- heteroaryl bromides with ethylene glycol, chlorination of the terminal alcohol, and dehydrohalogenation of the β-chloro ethers. Although not efficient in 2-hydroxy series, this method can be conveniently applied to the preparation of various aza-aryl vinyl ethers in moderate to good overall yields. [ABSTRACT FROM AUTHOR]

Abstract: Highly enantio- and exo-selective 1,3-dipolar cycloadditions of alanine-derived ketonitrones to E-crotonaldehyde could be realized in a good yield by the use of a chiral imidazolidinone salt without the addition of water. The origin of the stereoselectivity in the reaction was discussed and the absolute configuration of the cycloadduct determined unambiguously. [Copyright &y& Elsevier]

Abstract: Efficient access to masked β-amino-aldehydes was performed starting from 6-alcoxy tetrahydrooxazinone 6a–d (6-ATO). Transacetalization leads to the opening of the cycle to form either unsymmetric acetal 7 or symmetric acetals 16–18. These amino acetals are key compounds, obtained with 99% ee, which can be engaged in efficient peptide coupling. This method could easily provide peptides aldehydes or small amido aldehydes as exemplified with the formal synthesis of ent-Maraviroc. [Copyright &y& Elsevier]