scholarly journals Diastereoselective and enantioselective conjugate addition reactions utilizing α,β-unsaturated amides and lactams

2015 ◽  
Vol 11 ◽  
pp. 530-562 ◽  
Author(s):  
Katherine M Byrd
Keyword(s):  
Natural Products ◽  
Addition Reaction ◽  
Conjugate Addition ◽  
Addition Reactions ◽  
Pharmacological Agents ◽  
Carbon Carbon Bonds ◽  
Carbon Bonds

The conjugate addition reaction has been a useful tool in the formation of carbon–carbon bonds. The utility of this reaction has been demonstrated in the synthesis of many natural products, materials, and pharmacological agents. In the last three decades, there has been a significant increase in the development of asymmetric variants of this reaction. Unfortunately, conjugate addition reactions using α,β-unsaturated amides and lactams remain underdeveloped due to their inherently low reactivity. This review highlights the work that has been done on both diastereoselective and enantioselective conjugate addition reactions utilizing α,β-unsaturated amides and lactams.

scholarly journals (±)-trans-1,2-Cyclohexanediamine-Based Bis(NHC) Ligand for Cu-Catalyzed Asymmetric Conjugate Addition Reaction

Catalysts ◽  
2019 ◽  
Vol 9 (9) ◽  
pp. 780 ◽  
Author(s):  
Azusa Ishibashi ◽  
Shun Kamihigashi ◽  
Yuuki Iwai ◽  
Satoshi Sakaguchi
Keyword(s):  
Catalytic System ◽  
Amino Alcohol ◽  
Addition Reaction ◽  
Conjugate Addition ◽  
Addition Reactions ◽  
Chiral Ligand ◽  
Facial Selectivity ◽  
Ligand Precursors ◽  
Optically Pure

Bis(NHC) ligand precursors, L1, based on trans-1,2-diaminocyclohexane were designed and synthesized. To introduce chirality at the hydroxyamide side arm on the NHC of L1, a chiral β-amino alcohol, such as enantiopure leucinol, was used. Cu-catalyzed asymmetric conjugate addition reactions of cyclic and acyclic enones with Et2Zn were selected to evaluate the performance of L1 as a chiral ligand. For the reaction of cyclic enone, a combination of [bis(trimethylsilyl)acetylene]-(hexafluoroacetylacetonato)copper(I) (Cu(hfacac)(btmsa)) with a (±)-trans-1,2-cyclohexanediamine-based bis(NHC) ligand precursor, (rac; S,S)-L1, which was prepared from (S)-leucinol, was the most effective. Thus, treating 2-cyclohexen-1-one (3) with Et2Zn in the presence of catalytic amounts of Cu(hfacac)(btmsa) and (rac; S,S)-L1 afforded (R)-3-ethylcyclohexanone ((R)-4) with 97% ee. Similarly, use of (rac; R,R)-L1, which was prepared from (R)-leucinol, produced (S)-4 with 97% ee. Conversely, for the asymmetric 1,4-addition reaction of the acyclic enone, optically pure (−)-trans-1,2-cyclohexanediamine-based bis(NHC) ligand precursor, (R,R; S,S)-L1, worked efficiently. For example, 3-nonen-2-one (5) was reacted with Et2Zn using the CuOAc/(R,R; S,S)-L1 catalytic system to afford (R)-4-ethylnonan-2-one ((R)-6) with 90% ee. Furthermore, initially changing the counterion of the Cu precatalyst between an OAc and a ClO4 ligand on the metal reversed the facial selectivity of the approach of the substrates. Thus, the conjugate addition reaction of 5 with Et2Zn using the Cu(ClO4)2/(R,R; S,S)-L1 catalytic system, afforded (S)-6 with 75% ee.

Nomenclature of Lignans and Neolignans (IUPAC Recommendations 2000)

2000 ◽  
Vol 72 (8) ◽  
pp. 1493-1523 ◽  
Author(s):  
G. P. Moss
Keyword(s):  
Natural Products ◽  
Oxygen Atom ◽  
Benzene Ring ◽  
Carbon Bond ◽  
Large Group ◽  
Ether Oxygen Atom ◽  
Carbon Carbon Bond ◽  
Carbon Carbon Bonds ◽  
Carbon Bonds ◽  
Ether Oxygen

Lignans and neolignans are a large group of natural products characterized by the coupling of two C6C3 units. For nomenclature purposes the C6C3 unit is treated as propylbenzene and numbered from 1 to 6 in the ring, starting from the propyl group, and with the propyl group numbered from 7 to 9, starting from the benzene ring. With the second C6C3 unit the numbers are primed. When the two C6C3 units are linked by a bond between positions 8 and 8' the compound is referred to and named as a lignan. In the absence of the C-8 to C-8' bond, and where the two C6C3 units are linked by a carbon–carbon bond it is referred to and named as a neolignan. The linkage with neolignans may include C-8 or C-8'. Where there are no direct carbon–carbon bonds between the C6C3 units and they are linked by an ether oxygen atom the compound is named as an oxyneolignan. The nomenclature provides for the naming of additional rings and other modifications following standard organic nomenclature procedures for naming natural products. Provision is included to name the higher homologues. The sesquineolignans have three C6C3 units, and dineolignans have four C6C3 units.

Theoretical free energy profile and benchmarking of functionals for amino-thiourea organocatalyzed nitro-Michael addition reaction

2020 ◽  
Vol 22 (20) ◽  
pp. 11529-11536 ◽  
Author(s):  
Josefredo R. Pliego
Keyword(s):  
Free Energy ◽  
Michael Addition ◽  
Addition Reaction ◽  
Conjugate Addition ◽  
Catalytic Process ◽  
Addition Reactions ◽  
Energy Profile ◽  
Michael Addition Reaction ◽  
Free Energy Profile

Amino-thiourea organocatalysis is an important catalytic process for enantioselective conjugate addition reactions.

Application of Multi-component Reaction in the Synthesis of Heterocyclic [3.3.3] Propellane Derivatives

2022 ◽  
Vol 26 ◽  
Author(s):  
Zohreh Kheilkordi ◽  
Ghodsi Mahammadi Ziarani ◽  
Fatemeh Mohajer
Keyword(s):  
Natural Products ◽  
Heterocyclic Compounds ◽  
Pharmaceutical Compounds ◽  
Unique Structure ◽  
Carbon Carbon Bonds ◽  
Carbon Bonds

Abstract: Propellanes and derivatives have attractive properties due to their unique structure. Therefore, [3.3.3] propellanes, containing tricyclic structures with one of the carbon-carbon bonds common in three rings, were used in natural products, pharmaceutical compounds, and heterocyclic compounds, which were biologically important. The various multi-component reactions were applied in the synthesis of propellanes, which were highlighted throughout this review

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