Quadruple Reaction Research Articles

One-Pot Multicatalytic Approaches for the Synthesis of Cyclohepta[b]indoles, Indolotropones, and Tetrahydrocarbazoles.

Diversity oriented one-pot synthesis of cyclohepta[b]indoles, indolotropones, and tetrahydrocarbazoles (THCs) have been reported. Readily accessible 3-(2-aminophenyl)-5-hexenyn-3-ols under a one-pot trimetallic orthogonal catalysis furnish tetrahydrocyclohepta[b]indoles, and a one-pot quadruple reaction sequence of the enynols generates dihydrocyclohepta[b]indoles and indolotropones. During this study, formation of THCs was realized to be a reason for the yield loss in certain cases, this observation led to the development of a one-pot bimetallic approach for the synthesis of 1,3-disubstituted THCs.

Diastereoselective Synthesis of Functionalized Angularly‐Fused Tetracycles via an Organocatalytic Quadruple Reaction Sequence

AbstractAn efficient diastereoselective strategy to access complex structural tetracycles was described through an organocascade quadruple reaction sequence between (E)‐2‐(3‐arylallylidene)‐1H‐indene‐1,3(2H)‐diones and β‐keto esters. The reaction proceeded through remote 1,6‐addition followed by sequential 1,4‐addition and aldol/aldol reactions to generate angularly‐fused carbocyclic motifs with favourable to excellent yields (up to 94%) and diastereoselectivities (up to >20:1 dr). An enantioselective organocascade approach was attempted to yield densely functionalized tetracycles containing seven chiral centres including a quaternary centre.magnified image

Combining Organocatalysis and Lanthanide Catalysis: A Sequential One‐Pot Quadruple Reaction Sequence/Hetero‐Diels–Alder Asymmetric Synthesis of Functionalized Tricycles

AbstractA stereoselective one‐pot synthesis of functionalized complex tricyclic polyethers has been achieved using the combination of secondary amine and lanthanide catalysis. This one‐pot quadruple reaction/Hetero‐Diels–Alder sequence gave good yields (per step) as well as excellent diastereo‐ and enantioselectivities. Furthermore, the particular combination of lanthanide complexes with organocatalysis is one of the first examples described for sequential catalysis.

Combining Organocatalysis and Lanthanide Catalysis: A Sequential One-Pot Quadruple Reaction Sequence/Hetero-Diels-Alder Asymmetric Synthesis of Functionalized Tricycles.

A stereoselective one-pot synthesis of functionalized complex tricyclic polyethers has been achieved using the combination of secondary amine and lanthanide catalysis. This one-pot quadruple reaction/Hetero-Diels-Alder sequence gave good yields (per step) as well as excellent diastereo- and enantioselectivities. Furthermore, the particular combination of lanthanide complexes with organocatalysis is one of the first examples described for sequential catalysis.

ChemInform Abstract: Enantioselective Synthesis of Functionalized Polycarbocycles via a Three‐Component Organocascade Quadruple Reaction.

AbstractConditions for the scalable reaction of 1,3‐indanedione, 4‐substituted cyclohexanones and aryl or hetaryl aldehydes to form spirocyclic scaffolds with four stereogenic centers are elaborated.

Asymmetric Synthesis of Natural Products and Medicinal Drugs through One-Pot-Reaction Strategies

One-pot synthesis has become an important subject of modern synthetic chemistry owing to its efficiency, versatility and expediency in constructing complicated polycyclic ring systems, especially with a sustainable and catalytic aspect. This review aims to highlight the recent advances in this area with specific emphasis on the asymmetric synthesis of natural products and related core structures as well as medicinal drugs via one-pot operation. 1 Introduction 2 Double Reactions 3 Triple Reactions 4 Quadruple Reactions 5 Pot-Economy Reactions 6 Conclusions

Enantioselective Synthesis of Functionalized Polycarbocycles via a Three-Component Organocascade Quadruple Reaction.

An efficient organocascade quadruple reaction was conducted to synthesize a functionalized spiropolycyclic scaffold in high chemical yields (43-80%) and excellent levels of stereoselectivity (up to >19:1 dr and 99% ee). The quadruple reaction proceeded smoothly between 1,3-indanedione and aromatic aldehydes with concomitant desymmetrization of prochiral 4-substituted cyclohexanones through the Knoevenagel/Michael/aldol/aldol reaction sequence catalyzed by a bifunctional thiourea catalyst. Two of the formed products were transformed into spirocyclic epoxides containing four contiguous quaternary centers.

Total Synthesis of Isofregenedadiol

The first total synthesis of isofregenedadiol, a bicyclic diterpene isolated from H. Viscosum, is reported starting from a D-(-)-pantolactone chiral pool. A one-pot quadruple reaction sequence comprising an enyne ring-closing metathesis/cross-metathesis/Diels-Alder/aromatization for the construction of a target skeleton is the highlight of the present synthesis.

High yield of B-branch electron transfer in a quadruple reaction center mutant of the photosynthetic bacterium Rhodobacter sphaeroides.

A new reaction center (RC) quadruple mutant, called LDHW, of Rhodobacter sphaeroides is described. This mutant was constructed to obtain a high yield of B-branch electron transfer and to study P(+)Q(B)(-) formation via the B-branch. The A-branch of the mutant RC contains two monomer bacteriochlorophylls, B(A) and beta, as a result of the H mutation L(M214)H. The latter bacteriochlorophyll replaces bacteriopheophytin H(A) of wild-type RCs. As a result of the W mutation A(M260)W, the A-branch does not contain the ubiquinone Q(A); this facilitates the study of P(+)Q(B)(-) formation. Furthermore, the D mutation G(M203)D introduces an aspartic acid residue near B(A). Together these mutations impede electron transfer through the A-branch. The B-branch contains two bacteriopheophytins, Phi(B) and H(B), and a ubiquinone, Q(B.) Phi(B) replaces the monomer bacteriochlorophyll B(B) as a result of the L mutation H(M182)L. In the LDHW mutant we find 35-45% B-branch electron transfer, the highest yield reported so far. Transient absorption spectroscopy at 10 K, where the absorption bands due to the Q(X) transitions of Phi(B) and H(B) are well resolved, shows simultaneous bleachings of both absorption bands. Although photoreduction of the bacteriopheophytins occurs with a high yield, no significant (approximately 1%) P(+)Q(B)(-) formation was found.