Design, Synthesis, and Applications of Chiral <i>N</i>‑2-Phenyl-2-propyl Sulfinyl Imines for Group-Assisted Purification (GAP) Asymmetric Synthesis

A new chiral (<i>R_s</i>)-2-phenyl-2-propyl sulfinamide has been designed and synthesized; its derived aldimines and ketimines have been applied for asymmetric addition reaction with allylmagnesium bromide. The reaction was conveniently performed at room temperature to give a series of homoallylic amines in high yields (up to quant) and diastereoselectivity (up to >99% de). The pure products were obtained by relying on group-assisted purification (GAP) chemistry to avoid traditional purification methods of column chromatography or recrystallization. The conversion of disulfide to (<i>R</i>_<i>s</i>)-thiosulfinate which contains a newly generated polar group was also confirmed to be of the GAP chemistry in which washing crude product can generate pure enantiomer. The absolute stereochemistry has been determined by X-ray analysis

Design, Synthesis, and Applications of Chiral <i>N</i>‑2-Phenyl-2-propyl Sulfinyl Imines for Group-Assisted Purification (GAP) Asymmetric Synthesis

A new chiral (<i>R_s</i>)-2-phenyl-2-propyl sulfinamide has been designed and synthesized; its derived aldimines and ketimines have been applied for asymmetric addition reaction with allylmagnesium bromide. The reaction was conveniently performed at room temperature to give a series of homoallylic amines in high yields (up to quant) and diastereoselectivity (up to >99% de). The pure products were obtained by relying on group-assisted purification (GAP) chemistry to avoid traditional purification methods of column chromatography or recrystallization. The conversion of disulfide to (<i>R</i>_<i>s</i>)-thiosulfinate which contains a newly generated polar group was also confirmed to be of the GAP chemistry in which washing crude product can generate pure enantiomer. The absolute stereochemistry has been determined by X-ray analysis

Effect of Alcohol Structure on the Kinetics of Etherification and Dehydration over Tungstated Zirconia.

Linear and branched ether molecules have attracted recent interest as diesel additives and lubricants that can be produced from biomass-derived alcohols. In this study, tungstated zirconia was identified as a selective and green solid acid catalyst for the direct etherification of primary alcohols in the liquid phase, achieving ether selectivities of &gt;94 % for C6 -C12 linear alcohol coupling at 393 K. The length of linear primary alcohols (C6 -C12 ) was shown to have a negligible effect on apparent activation energies for etherification and dehydration, demonstrating the possibility to produce both symmetrical and asymmetrical linear ethers. Reactions over a series of C6 alcohols with varying methyl branch positions indicated that substituted alcohols (2°, 3°) and alcohols with branches on the β-carbon readily undergo dehydration, but alcohols with branches at least three carbons away from the -OH group are highly selective to ether. A novel model compound, 4-hexyl-1dodecanol, was synthesized and tested to further demonstrate this structure-activity relationship. Trends in the effects of alcohol structure on selectivity were consistent with previously proposed mechanisms for etherification and dehydration, and help to define possible pathways to selectively form ethers from biomass-derived alcohols

Asymmetric Carbamoyl Anion Additions to Chiral <i>N</i>‑Phosphonyl Imines via the GAP Chemistry Process and Stereoselectivity Enrichments

Carbamoyl anions were found to smoothly react with chiral <i>N</i>-phosphonyl imines in toluene at −78 °C to r.t. using LiHMDS as the base. Group-assisted purification (GAP) has been utilized to give the pure amides without using column chromatography or recrystallization. The asymmetric reaction resulted in chiral <i>N</i>-phosphonyl amino amides with good to excellent yields (71–99%) and good crude diastereoselectivities (<i>dr</i> 84:16–95:5). In this GAP procedure, the crude solids are washed with diethyl ether to afford the pure products, as revealed by ¹H NMR analysis; GAP washing consistently increases the diastereopurity of the products, resulting in excellent diastereoselectivities, often with final <i>dr</i> > 99:1. Interestingly, the diastereoenriched products can be obtained either in the ether solution or as the suspended solid, depending on the substrate

Exploration of Ethanol-to-Butadiene Catalysts by High-Throughput Experimentation and Machine Learning

Meeting the high demand for synthetic rubbers and elastomers requires a cost-effective source of 1,3-butadiene, making on-purpose synthesis from ethanol a crucial process. To tackle this challenge, a comprehensive multi-elemental approach was employed in conjunction with a genetic algorithm-driven high-throughput experimentation technique. The study explored a vast catalyst space, comprising up to 14 elements - including Mg, Al, Cr, Ni, Cu, Zn, Ga, Y, Zr, Nb, Mo, Ag, La, and Hf - co-supported on mesoporous silica, with the aims to discover effective combinations and understand the roles of each element in the overall reaction mechanism. The discovered efficient catalysts were composed of primarily Mg, Zn, Y, and Hf, and secondary Zr, Nb, and La. Such highly multi-elemental design was suggested to achieve a balance for the complex reactions of ETB, where efficient conversion of acetaldehyde to butadiene while minimizing the production of ethylene was critical. The highest yield obtained was 73% for butadiene. Through the application of machine learning techniques on the collected dataset, we successfully derived important insights related to catalyst design and catalysis. In particular, we proposed a visualization method to facilitate a deeper understanding of the role of each element in the overall catalysis

Written on the Floor: Shared Theatre Space as Palimpsest

Efficient domino approaches for the synthesis of multifunctionalized tricyclic fused pyrroles and dibenzo[<i>b</i>,<i>e</i>][1,4]diazepin-1-ones have been established. The reaction pathways were controlled by varying enaminones with different substituted patterns to give a series of new fused pyrroles and dibenzo[<i>b</i>,<i>e</i>][1,4]diazepin-1-ones selectively. The complete <i>anti</i> diastereoselectivity was achieved for the first reaction

Parameterization of Acyclic Diaminocarbene Ligands Applied to a Gold(I)-Catalyzed Enantioselective Tandem Rearrangement/Cyclization

Computed descriptors for acyclic diaminocarbene ligands are developed in the context of a gold catalyzed enantioselective tandem [3,3]-sigmatropic rearrangement-[2+2]-cyclization. Surrogate structures enable the rapid identification of parameters that reveal mechanistic characteristics. The observed selectivity trends are validated in a robust multivariate analysis facilitating the development of a highly enantioselective process