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

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

Three-Component Domino Reactions for Selective Formation of Indeno[1,2‑<i>b</i>]indole Derivatives

Efficient three-component domino strategies for the synthesis of multifunctionalized tetracyclic indeno[1,2-<i>b</i>]indole derivatives with different substituted patterns have been established successfully. The first pathway involves a novel sequential methyl migration, aromatization, and esterification, while a second reaction in HOAc leads to compounds <b>6</b> with high <i>syn</i> diastereoselectivity. Both reactions showed attractive features including mild conditions, convenient one-pot operation, short reaction times of 15–32 min, and excellent regio- and/or stereoselectivity

Three-Component Domino Reactions for Selective Formation of Indeno[1,2‑<i>b</i>]indole Derivatives

Efficient three-component domino strategies for the synthesis of multifunctionalized tetracyclic indeno[1,2-<i>b</i>]indole derivatives with different substituted patterns have been established successfully. The first pathway involves a novel sequential methyl migration, aromatization, and esterification, while a second reaction in HOAc leads to compounds <b>6</b> with high <i>syn</i> diastereoselectivity. Both reactions showed attractive features including mild conditions, convenient one-pot operation, short reaction times of 15–32 min, and excellent regio- and/or stereoselectivity

Three-Component Domino Reactions for Selective Formation of Indeno[1,2‑<i>b</i>]indole Derivatives

Efficient three-component domino strategies for the synthesis of multifunctionalized tetracyclic indeno[1,2-<i>b</i>]indole derivatives with different substituted patterns have been established successfully. The first pathway involves a novel sequential methyl migration, aromatization, and esterification, while a second reaction in HOAc leads to compounds <b>6</b> with high <i>syn</i> diastereoselectivity. Both reactions showed attractive features including mild conditions, convenient one-pot operation, short reaction times of 15–32 min, and excellent regio- and/or stereoselectivity

Group-Assisted Purification Chemistry for Asymmetric Mannich-type Reaction of Chiral <i>N</i>‑Phosphonyl Imines with Azlactones Leading to Syntheses of α‑Quaternary α,β-Diamino Acid Derivatives

An asymmetric Mannich-type reaction between chiral <i>N</i>-phosphonyl imines and azlactones [oxazol-5­(4<i>H</i>)-ones] has been established under convenient conditions at room temperature. The reaction was performed without using any bases, additives, or catalysts to achieve up to excellent chemical yields and diastereoselectivity for 32 examples. The α-quaternary <i>syn</i>-α,β-diamino acid products were purified simply by washing the crude mixtures with cosolvents, following the group-assisted purification chemistry/technology, without involving traditional chromatography or recrystallization methods. The auxiliary can be readily removed and recycled for reuse. The absolute configuration was unambiguously assigned by X-ray structural analysis

Three-Component Domino Reactions for Selective Formation of Indeno[1,2‑<i>b</i>]indole Derivatives

Efficient three-component domino strategies for the synthesis of multifunctionalized tetracyclic indeno[1,2-<i>b</i>]indole derivatives with different substituted patterns have been established successfully. The first pathway involves a novel sequential methyl migration, aromatization, and esterification, while a second reaction in HOAc leads to compounds <b>6</b> with high <i>syn</i> diastereoselectivity. Both reactions showed attractive features including mild conditions, convenient one-pot operation, short reaction times of 15–32 min, and excellent regio- and/or stereoselectivity

Cobalt-Catalyzed Decarboxylative C–H (Hetero)Arylation for the Synthesis of Arylheteroarenes and Unsymmetrical Biheteroaryls

A cobalt-catalyzed decarboxylative cross-coupling reaction of (hetero)­aryl carboxylic acids with benzothiazoles or benzoxazoles is reported. This represents a first example of metal-catalyzed decarboxylative C–H heteroarylation of benzo-fused heterocycles. The transformation provides a convenient route, with good yields and functional group tolerance, to various important arylheteroaryl and unsymmetrical biheteroaryl structural motifs

Asymmetric Catalytic Enantio- and Diastereoselective Boron Conjugate Addition Reactions of α‑Functionalized α,β-Unsaturated Carbonyl Substrates

An efficient catalytic system has been established for the asymmetric boron conjugate addition of B₂pin₂ onto α-functionalized (involving C, N, O, and Cl) α,β-unsaturated carbonyls under mild, neutral conditions involving Cu­[(<i>S</i>)-(<i>R</i>)-ppfa]­Cl, AgNTf₂, and alcohols. The dual additives of AgNTf₂ and alcohols were found to play crucial roles for achieving high catalytic activity and enantio- and diastereoselectivity (up to 98% ee and 70:1 dr)