Isothiourea-Catalysed Acylative Dynamic Kinetic Resolution of Tetra-substituted Morpholinone and Benzoxazinone Lactols

The development of methods to allow the selective acylative dynamic kinetic resolution (DKR) of tetra-substituted lactols is a recognised synthetic challenge. In this manuscript, a highly enantioselective isothiourea-catalysed acylative DKR of tetra-substituted morpholinone and benzoxazinone-derived lactols is reported. The scope and limitations of this methodology have been developed, with high enantioselectivity and good to excellent yields (up to 89 %, 99 : 1 er) observed across a broad range of substrate derivatives incorporating substitution at N(4) and C(2), di- and spirocyclic substitution at C(5) and C(6), as well as benzannulation (>35 examples in total). The DKR process is amenable to scale-up on a 1 g laboratory scale. The factors leading to high selectivity in this DKR process have been probed through computation, with an N-C=O⋅⋅⋅isothiouronium interaction identified as key to producing ester products in highly enantioenriched form.

FTIR and DFT studies of LiTFSI solvation in 3-methyl-2-oxazolidinone

Combined computational/FTIR spectroscopic analyses of 3-methyl-2-oxazolidinone (NMO) solutions with varying molar ratios of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) are reported. Based on the second derivative spectral profile, overlapping peaks are distinguished as well as assigned to the vibrational modes of implicitly and explicitly interacting NMO molecules. Thereby, the geometry of a monomeric, a dimeric and a simplified solvation structure [Li(NMO)1](+) are optimized with a polarizable continuum model at a B3LYP theoretical level. With increasing contents of LiTFSI, the formation of Li(+) solvation structures is scrutinized by semi-quantitative analysis of deconvoluted integral peak areas for three different ring-related vibrations and C=O-stretch vibration. A discrepancy in the obtained data is observed implying the influence of the TFSI anion the ring-related vibrations are prone to. The solvation number of 4 is determined according to the C=O-signal in diluted solution, which is proven by the computed Gibbs free energy for solvation of [Li(NMO)4](+) in a NMO medium (-41.7 kcal mol(-1)).

Formation of α-chalcogenyl acrylamides through unprecedented chalcogen-mediated metal-free oxyfunctionalization of ynamides with DMSO as an oxidant

A novel chalcogen-mediated metal-free oxyfunctionalization mode of ynamides for the synthesis of α-chalcogenyl acrylamides has been developed.