scholarly journals Bioinspired total synthesis of katsumadain A by organocatalytic enantioselective 1,4-conjugate addition

2013 ◽  
Vol 9 ◽  
pp. 1601-1606 ◽  
Author(s):  
Yongguang Wang ◽  
Ruiyang Bao ◽  
Shengdian Huang ◽  
Yefeng Tang
Keyword(s):  
Influenza Virus ◽  
Total Synthesis ◽  
Michael Addition ◽  
Conjugate Addition ◽  
Naturally Occurring ◽  
Influenza Virus Neuraminidase

Katsumadain A, a naturally occurring influenza virus neuraminidase (NA) inhibitor, was synthesized by using a bioinspired, organocatalytic enantioselective 1,4-conjugate addition of styryl-2-pyranone with cinnamaldehyde, followed by a tandem Horner–Wadsworth–Emmons/oxa Michael addition.

scholarly journals Oxazolidinones as Chiral Auxiliaries in the Asymmetric 1,4-Conjugate Addition Reaction Applied to the Total Synthesis of Natural Products: A Supplemental Mini-Review

2018 ◽  
Vol 15 (1) ◽  
pp. 3-20 ◽  
Author(s):  
Vahideh Zadsirjan ◽  
Majid M. Heravi
Keyword(s):  
Total Synthesis ◽  
Biological Activities ◽  
Conjugate Addition ◽  
Chiral Auxiliary ◽  
Addition Reactions ◽  
Chiral Auxiliaries ◽  
Complex Molecules ◽  
Total Syntheses ◽  
Naturally Occurring ◽  
Wide Range

Background: The most frequently used chiral auxiliaries, oxazolidinones (Evans' oxazolidinones) have been employed in 1,4-congugate addition reactions to α,β-unsaturated carbonyl compounds. Supplementary to our previous reports in this mini-review, we attempted to underscore the applications of this strategy in a step (steps) in the total synthesis of some naturally occurring compounds exhibiting diverse biological activities. Objective: In this mini-review, we try to underscore the applications of oxazolidinones (Evans’ oxazolidinones) in 1,4-congugate addition reactions to α,β-unsaturated carbonyl in the total synthesis of some naturally occurring compounds exhibiting diverse biological activities. Conclusion: In spite of well-known superiority of asymmetric catalyzed reactions, the use of auxiliarycontrolled reactions are still considered as commanding, vital and sometimes as only tools in the generation of stereogenic centers during the construction of complex molecules and total synthesis of naturally occurring compounds. The commercial availability, or readily accessibility of a wide variety of chiral amino alcohols as starting materials to synthesize a wide range of oxazolidinones is the merits of them. In addition, the ease of removal and subjection to various and diverse stereoselective reactions make oxazolidinones as the ideal and superior chiral auxiliaries. In this regard, they were successfully used in asymmetric 1,4-conjugate addition reactions with high stereoselectivities. The high degree of asymmetric induction can be attributed to the rigid chelation of N-acyloxazolidinones with metal ions, as well as the covering of one face of the system by the bulkiness of 4-substituent. In summary, in this report, the importance of the applications of chiral oxazolidinones as suitable chiral auxiliaries in the stereoselective, 1,4-conjugate addition reactions in asymmetric synthesis and in particular, the total synthesis of naturally occurring compounds and some complex molecules were underscored. Noticeably, in these total syntheses, this chiral auxiliary is controlling the stereochemistry of a newly created stereogenic center as well as preserving the configuration of other chiral centers, which already have been presented in the precursor. General methods have been established for the attachment of the chiral auxiliary as a moiety to the substrate molecule in high to excellent yields. At the end of these reactions, this auxiliary can be easily removed leaving various desired reactive motifs for the next step in multi-step synthesis.

Total Synthesis of Macaranin B

2021 ◽  
Author(s):  
Shintaro Matsumoto ◽  
Akio Aoyama ◽  
Shinnosuke Wakamori ◽  
Hidetoshi Yamada
Keyword(s):  
Total Synthesis ◽  
Michael Addition ◽  
Oxidative Coupling ◽  
Coupling Reaction ◽  
Oxidative Coupling Reaction ◽  
Naturally Occurring ◽  
Key Steps

Abstract This study describes the total synthesis of macaranin B, a naturally occurring ellagitannin containing 1-O-galloyl and 3,6-O-macaranoyl groups in an axial-rich D-glucose. The Key steps of the synthesis include an oxidative coupling reaction of galloyl groups with 1,2,4-orthoacetylglucose moiety and oxa-Michael addition/elimination using an orthoquinone monoketal. This facilitates the construction of the macaranoyl group and the first total synthesis of macaranin B.

Carbon atom insertion bicycloannulation: total syntheses of ishwarane and ishwarone

1984 ◽  
Vol 62 (10) ◽  
pp. 1908-1921 ◽  
Author(s):  
Robert M. Cory ◽  
Lester P. J. Burton ◽  
Dominic M. T. Chan ◽  
Fred R. McLaren ◽  
Mary H. Rastall ◽  
...  
Keyword(s):  
Carbon Atom ◽  
Total Synthesis ◽  
Conjugate Addition ◽  
Diels Alder ◽  
Magnesium Bromide ◽  
Total Syntheses ◽  
Tertiary Alcohols ◽  
Naturally Occurring ◽  
Carbene Insertion ◽  
Equivalent Sequence

Insertion of a carbon atom into a methyl cyclohexene, leading in a single synthetic step to a bicyclo[3.2.1.02.7]octane by carbene addition to the double bond and carbene insertion into a methyl C—H bond, has been accomplished by treating the cyclohexene with carbon tetrabromide and methyllithium at low temperatures. This new bicycloannulation method has been employed in a total synthesis of ishwarane (1), the naturally occurring parent hydrocarbon of the ishwarane class of tetracyclic sesquiterpenes. Although this reaction was not successful with various possible precursors of ishwarone (2), this natural product was prepared in low yield by a two-step version of the carbon atom insertion bicycloannulation (CAIB) procedure involving addition of bromoform-derived dibromocarbene to the octalone (5) followed by treatment of the resulting dibromocyclopropane (56) with methyllithium. The same two-step sequence was also successful in the first synthesis of norishwarane (20), the hydrocarbon comprising the bare ring system of the ishwarane sesquiterpenoids. The Diels–Alder synthesis used in the preparation of the octalin precursor (18) of norishwarane could not be used for the terpenes themselves because of the lack of dienophilic reactivity of the required cyclohexenone (7). A regioselective Diels–Alder equivalent sequence was therefore developed, consisting of conjugate addition of lithium di(3-methyl-3-butenyl)cuprate (42) to 2,3,4-trimethylcyclohex-2-en-1-one (7), epoxidation, base-catalyzed cyclization of the resulting epoxide (47) to a mixture of primary and tertiary alcohols (50 and 49, respectively), and dehydration of 49 to give 5. In the case of ishwarane, the octalin precursor (62) was synthesized by conjugate addition of lithium dimethylcuprate to octalone 59, addition of methyl magnesium bromide to the resulting decalone (60) to give octalol 61, and dehydration.

Organometallics in prostaglandin synthesis

1988 ◽  
Vol 326 (1592) ◽  
pp. 579-585 ◽  
Keyword(s):  
Conjugate Addition ◽  
Prostaglandin Synthesis ◽  
Side Chain ◽  
Prostaglandin E ◽  
Controlled Synthesis ◽  
One Pot ◽  
Naturally Occurring ◽  
Chain Unit ◽  
Alkyl Iodides

An extremely short way to prostaglandins has been opened by combining the newly devised organometallic methodologies. Convergent, one-pot creation of the prostanoid framework is achieved by organocopper conjugate addition of the S-configurated ω-side-chain unit to (R)-4-trialkylsiloxy-2-cyclopentenone followed by the organotin-aided trapping of the enolate intermediate by α-side-chain alkyl iodides. Prostaglandin E 2 can be prepared in only three steps from the chiral building units. The protected 5,6-didehydro-PGE 2 derivatives thus obtained serve as common intermediates for the synthesis of a variety of naturally occurring prostaglandins including prostacyclin. This approach is also useful for the controlled synthesis of isocarbacyclin.

Total Synthesis of (±)-α- and β-Lycoranes by Sequential Chemoselective Conjugate Addition−Stereoselective Nitro-Michael Cyclization of an ω-Nitro-α,β,ψ,ω-unsaturated Ester

2003 ◽  
Vol 5 (7) ◽  
pp. 1123-1126 ◽  
Author(s):  
Tomohisa Yasuhara ◽  
Katsumi Nishimura ◽  
Mitsuaki Yamashita ◽  
Naoshi Fukuyama ◽  
Ken-ichi Yamada ◽  
...  
Keyword(s):  
Total Synthesis ◽  
Conjugate Addition ◽  
Unsaturated Ester
Sign in / Sign up

Export Citation Format

Share Document