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A convenient and efficient synthetic method has been developed to construct highly functionalized polycyclic indoline skeletons with four contiguous stereocenters, which are of great importance in biological and pharmaceutical chemistry. The selective formation of either the oxabridged-ring or ring-opening polycyclic indoline derivatives can be controlled by using different gold catalytic systems. A variety of polycyclic indoline derivatives were obtained in moderate to good yields under mild conditions with moderate to excellent enantioselectivity. [ABSTRACT FROM AUTHOR]

Rh(ii)-catalyzed diversified ring expansions controlled by single-electron-transfer (SET) have been disclosed in this communication, producing a series of indole-fused azetidines and 1H-carbazoles or related derivatives in moderate to good yields via Rh2III,II nitrene radical intermediates. The direction of ring expansion branches according to different ring sizes of methylenecycloalkanes. [ABSTRACT FROM AUTHOR]

A facile synthetic method to access 3-substituted isoquinoline or dihydroisoquinoline derivatives has been developed via a novel cyclization reaction of N-sulfonyl-1,2,3-triazole derivatives by thermally induced rearrangement. [ABSTRACT FROM AUTHOR]

Novel Cr(iii) catalysts supported by PNPO phosphazane ligands of the type Ph2PN(R)P(Ph)OAr have been prepared, all of which, upon activation with MMAO-3A, are highly active in ethylene tri-/tetramerization with considerable selectivity. The effect of ligand substitution on the catalytic performance has been examined. The Cr precatalyst supported by the PNPO phosphazane ligand with an N-cyclohexyl achieved high activity of 316.7 kg (g Cr h−1)−1 and a high total selectivity of 85.1% towards valuable 1-hexene (45.7%) and 1-octene (39.4%) using chlorobenzene as the solvent at 35 bar and 40 °C. In methylcyclohexane, the precatalyst supported by [Ph2PN(iPr)P(Ph)OPh] exhibited a higher 1-octene selectivity (54.0%) with a considerable activity of 73.3 kg (g Cr h−1)−1 at 35 bar and 40 °C. With the fine-tuned ligand backbone, such a PNPO phosphazane-based catalyst system provides a mode for precise understanding of the impact of ligand variations on catalytic performance. [ABSTRACT FROM AUTHOR]

The chemoselective [4+2] vs. [2+2] cycloaddition between allenoates and dithioesters can be controlled by switching the nucleophilic amine catalyst. The two modes of cyclizations represent the first example of controllable and chemoselective annulations between allenoates and dienophiles catalyzed by amine. These cyclizations are useful in offering a divergent synthesis of sulfur-containing heterocycles. On the basis of this investigation, it can be realized that dithioesters with a vicinal electron-withdrawing group can react not only like a Michael acceptor but also as a ketone or imine. [ABSTRACT FROM AUTHOR]

The first series of chiral phosphine-imidazole carbene ligands based on a 1,1′-binaphthyl framework were synthesized from (R)-2-amine-2′-(diphenylphosphino)-1,1′-binaphthyl (1) in a four-step pathway. After deprotonation of these phosphine-imidazolium salts with LiOtBu, and subsequent complexation with [Ir(COD)Cl]2 and anion exchange with NaBArF, phosphine-carbene chelated iridium complexes (R)-6a and (R)-6b were obtained. Their structures have been characterized by NMR and X-ray diffraction analysis. The NHC-phosphine rhodium complex (R)-6c has been also obtained by a similar synthetic method. These iridium complexes have been applied to catalyze the asymmetric hydrogenation of alkenes to give the corresponding products in moderate to excellent conversion (up to 99%) and moderate enantioselectivities under mild conditions (up to 61% ee). [ABSTRACT FROM AUTHOR]

Chiral N-phosphonyl imines were found to be efficient electrophiles for reaction with diethylaluminium cyanide, a non-volatile and inexpensive cyanide source. The reaction produced chiral Strecker adducts, α-aminonitriles, in excellent chemical yields (94–98%) and diastereoselectivities (95 : 5 to >99%). This synthesis was confirmed to follow the GAP chemistry (group-assistant-purification chemistry) process, which can avoid traditional chromatography and recrystallization purifications, i.e., the pure chiral α-aminonitriles bearing a chiral N-phosphonyl group can be simply obtained by washing the solid crude products with hexane. The chiral N-phosphonyl auxiliary can be easily cleaved under mildly acidic conditions and quantitatively recycled by a one-time extraction with n-butanol. [ABSTRACT FROM AUTHOR]

Chiral N-phosphonyl imines were found to be efficient electrophiles for reaction with diethylaluminium cyanide, a non-volatile and inexpensive cyanide source. The reaction produced chiral Strecker adducts, α-aminonitriles, in excellent chemical yields (94–98%) and diastereoselectivities (95 : 5 to ＞99%). This synthesis was confirmed to follow the GAP chemistry (group-assistant-purification chemistry) process, which can avoid traditional chromatography and recrystallization purifications, i.e., the pure chiral α-aminonitriles bearing a chiral N-phosphonyl group can be simply obtained by washing the solid crude products with hexane. The chiral N-phosphonyl auxiliary can be easily cleaved under mildly acidic conditions and quantitatively recycled by a one-time extraction with n-butanol. [ABSTRACT FROM AUTHOR]

Three ruthenium complexes bearing backbone-monosubstituted CAACs were prepared and displayed dramatic improvement in catalytic efficiency not only in RCM reaction but also in the ethenolysis of methyl oleate, compared to those bearing backbone-disubstituted CAACs. [ABSTRACT FROM AUTHOR]

Enantioselective Pd(ii)-catalyzed construction of [3.3.1]-bicyclic ketals from 2-hydroxyphenylboronic acid 1 and enone 3 is reported, yielding enantioenriched [3.3.1]-bicyclic ketals in up to 97% yields and 98% ee. [ABSTRACT FROM AUTHOR]

A versatile and modular method for the preparation of various backbone-substituted, functionalized and chiral imidazolinium salts from the reaction of formamidines with alkene oxides has been described, providing a more straightforward access to substituted imidazolinium salts than the previously reported methods. [ABSTRACT FROM AUTHOR]

A novel phosphine-catalyzed highly diastereoselective [3+2] cycloaddition of isatin derived α,β-unsaturated ketones with α-allenic ester has been developed. [ABSTRACT FROM AUTHOR]