Studies towards the Total Synthesis of Kadcotrione B

Synthesis ◽  
2019 ◽  
Vol 52 (05) ◽  
pp. 735-743
Author(s):  
Julakanti Satyanarayana Reddy ◽  
Marri Gangababu ◽  
Patel Manimala ◽  
Aluru Rammohan ◽  
Jillu Singh Yadav
Keyword(s):  
Total Synthesis ◽  
Michael Addition ◽  
Aldol Condensation ◽  
Aldol Reaction ◽  
Side Chain ◽  
Wacker Oxidation ◽  
Efficient Approach ◽  
Salient Features ◽  
Robinson Annulation

A convergent and efficient approach towards the total synthesis of Kadcotrione B is described. For this purpose, the syntheses of two fragments, 6/6/5-fused tricyclic ring and C-9 side chain, were accomplished. The salient features of these syntheses are the utilization of aldol condensation, Evans aldol reaction, Horner–Wadsworth–Emmons olefination, Michael addition, Robinson annulation, and Wacker oxidation.

scholarly journals Toward the total synthesis of ritterazine N

2008 ◽  
Vol 80 (5) ◽  
pp. 1141-1148 ◽  
Author(s):  
Douglass F. Taber ◽  
Jean-Michel Joerger ◽  
Karen V. Taluskie
Keyword(s):  
Total Synthesis ◽  
Aldol Condensation ◽  
Side Chain ◽  
Tricyclic Core

Zr-mediated equilibrating cyclocarbonylation of a designed triene led with high diastereocontrol to the ABC 6-6-5 tricyclic core of ritterazine N. The 5-5 EF spiroketal side chain of ritterazine N was prepared by equilibrating cyclization of an acyclic keto diol. The two components were coupled, and the D ring was assembled by intramolecular aldol condensation.

Synthesis of Polycyclic Frameworks through Iron-Catalyzed Intramolecular [5+2] Cycloaddition

Synlett ◽  
2018 ◽  
Vol 29 (15) ◽  
pp. 1978-1982 ◽  
Author(s):  
Shaomin Fu ◽  
Bo Liu ◽  
Yongjiang Liu ◽  
Yanhui Zhang ◽  
Xiao Wang
Keyword(s):  
Claisen Rearrangement ◽  
Aldol Reaction ◽  
Diterpenoid Alkaloids ◽  
Wacker Oxidation ◽  
Efficient Approach ◽  
The Core ◽  
Grignard Addition ◽  
Tetracyclic Core

A concise and efficient approach to the core of the C18/C19 diterpenoid alkaloids and phomopsterone B is reported. Both syntheses share the same iron-catalyzed intramolecular [5+2] cycloaddition to assemble the tricyclo[6.3.1.01,6]]dodecane skeleton. The following ­approach to the 6/5/6/7 tetracyclic core scaffold of C18/C19 diterpenoid alkaloids features a regioselective Grignard addition/thermal Claisen rearrangement/RCM cyclization. Meanwhile the synthetic steps to access the spiro 6/5/6 tricyclic subunits of phomopsterone B were characterized as intramolecular aldol reaction, Wacker oxidation, and Criegee ­reaction.

A One-Pot Intramolecular Tandem Michael–Aldol Annulation Reaction for the Synthesis of Chiral Pentacyclic Terpenes

Synthesis ◽  
2019 ◽  
Vol 51 (21) ◽  
pp. 3964-3972
Author(s):  
Jianyu Lu ◽  
Serkan Koldas ◽  
Huafang Fan ◽  
John Desper ◽  
Victor W. Day ◽  
...  
Keyword(s):  
Michael Addition ◽  
Aldol Condensation ◽  
Crystallographic Analysis ◽  
Side Chain ◽  
One Pot ◽  
X Ray ◽  
Double Ring ◽  
Stereogenic Centers

A chiral tricyclic terpene possessing a 6,6,6-tricyclic framework and a 3,3-dimethyl-7-oxooctylidenyl side chain undergoes a double ring-closing reaction to give two chiral pentacyclic terpenes in a ratio of 4:3 via an intramolecular Michael addition followed by aldol condensation under basic conditions. Three new stereogenic centers are introduced in the initial Michael annulation reaction. Stereoselective installation of an ethoxycarbonyl group at C17 of the two pentacyclic terpenes separately gives the corresponding highly functionalized pentacyclic terpenoids with seven stereogenic centers. The structures and stereochemistry of key intermediates and products are established through X-ray crystallographic analysis. A mechanism is proposed for explaining the stereochemistry in the Michael annulation reaction.

BF3·OEt2-Catalyzed Aldol Condensation of Steroid Sapogenins and 2-Oxoacids: A Single Step Conversion of Steroid Spiroketals into Branched α,β-Unsaturated Spirolactones

Synthesis ◽  
2020 ◽  
Vol 52 (15) ◽  
pp. 2241-2244
Author(s):  
Martin A. Iglesias-Arteaga ◽  
Juan E. Hernández-Martínez
Keyword(s):  
Pyruvic Acid ◽  
Aldol Condensation ◽  
Aldol Reaction ◽  
Glyoxylic Acid ◽  
2D Nmr ◽  
Single Step ◽  
Side Chain ◽  
The Novel ◽  
Nmr Techniques ◽  
Plausible Mechanism

BF3·OEt2-catalyzed aldol reaction of steroid sapogenins with glyoxylic acid or pyruvic acid led to compounds in which the novel spirocyclic side chain bears an α,β-unsaturated lactone. The structures of the new spirolactones were established with the aid of combined 1D and 2D NMR techniques. A plausible mechanism is described.

Total Synthesis of PF1163B

Synlett ◽  
2019 ◽  
Vol 30 (06) ◽  
pp. 709-712 ◽  
Author(s):  
Seijiro Hosokawa ◽  
Aakash Sengupta
Keyword(s):  
Amino Acid ◽  
Total Synthesis ◽  
Aldol Reaction ◽  
Carbon Chain ◽  
Side Chain ◽  
Synthetic Route ◽  
Major Isomer ◽  
Proton Source ◽  
Mukaiyama Aldol ◽  
Moderate Yield

A total synthesis of PF1163B has been achieved. The vinylogous Mukaiyama aldol reaction of ketene silyl N,O-acetal 6 (ent-6) mediated by excess TiCl4 proceeded with saturated aldehydes to give adduct 10 in moderate yield with moderate stereoselectivity. The major isomer is the diastereomer that was provided by using one equivalent of TiCl4. The Birch reduction of α,β-unsaturated imide 4, possessing a less hindered side chain, gave 12 in good stereoselectivity by employing 2-isopropylbenzimidazole as a bulky proton source. After elongation of the carbon chain and connection with the amino acid part, we accomplished a total synthesis of PF1163B. These methods constitute a concise synthetic route to obtain polyketides as well as depsipeptides.

Chemoenzymatic total synthesis of ent-neopinone and formal total synthesis of ent-codeinone from β-bromoethylbenzene*

2011 ◽  
Vol 89 (6) ◽  
pp. 709-729 ◽  
Author(s):  
Jan Duchek ◽  
T. Graeme Piercy ◽  
Jacqueline Gilmet ◽  
Tomas Hudlicky
Keyword(s):  
Total Synthesis ◽  
Heck Reaction ◽  
Aldol Condensation ◽  
Side Chain ◽  
Prins Reaction ◽  
Toluene Dioxygenase ◽  
E Coli ◽  
Key Steps ◽  
New Compounds ◽  
Stereogenic Center

Formal total synthesis of ent-codeinone and ent-codeine was accomplished via the total synthesis of ent-neopinone attained in 14 steps from β-bromoethylbenzene. The key steps included (i) enzymatic dihydroxylation of β-bromoethylbenzene with E. coli JM109 (pDTG601a), an organism that overexpresses toluene dioxygenase, (ii) a Heck reaction to establish C-13 stereogenic center, (iii) aldol condensation, and (iv) 1,6-conjugate addition of the ethylamino side chain to C-9. Several other modes of construction of the C-9 and C-14 centers were also investigated: Mannich cyclization, and aza-Prins reaction. The synthesis of ent-codeinone was formalized by intersecting Fukuyama’s recently published approach. Experimental and spectral data are provided for all new compounds.

Total Synthesis of a Hemiacetal Polypropionate from Siphonaria australis

2004 ◽  
Vol 57 (8) ◽  
pp. 787 ◽  
Author(s):  
Troy Lister ◽  
Michael V. Perkins
Keyword(s):  
Total Synthesis ◽  
Spectroscopic Data ◽  
Aldol Condensation ◽  
Optical Rotation ◽  
Trimethylsilyl Ether ◽  
Side Chain ◽  
Relative Configuration ◽  
Stereocontrolled Synthesis ◽  
Mukaiyama Aldol ◽  
Acyclic Precursor

A highly stereocontrolled synthesis of (2S,3R,5R,6S)-6-[(1E,3R)-1,3-dimethylhex-1-enyl]-2-ethyl-2-hydroxy-3,5-dimethyltetrahydro-4H-pyran-4-one has been achieved in 13 steps and an overall yield of 7.6% from (R)-(+)-4-benzyloxazolidin-2-one. This substrate-controlled asymmetric synthesis utilized Paterson’s lactate-derived chiral ketone (2S)-2-(benzoyloxy) pentan-3-one to generate the 5R and 6S stereocentres and alkylation of an Evans’ auxiliary to generate the remote side-chain 3R stereocentre. Furthermore, a novel, highly efficient, and selective strategy was used to generate an enol trimethylsilyl ether whose subsequent Mukaiyama aldol condensation gave the acyclic precursor to the final product. A thermodynamically controlled cyclization then gave (2S,3R,5R,6S)-6-[(1E,3R)-1,3-dimethylhex-1-enyl]-2-ethyl-2-hydroxy-3,5-dimethyltetrahydro-4H-pyran-4-one with control of the 2S and 3R stereocentres. The NMR spectroscopic data and optical rotation obtained for synthetic (2S,3R,5R,6S)-6-[(1E,3R)-1,3-dimethylhex-1-enyl]-2-ethyl-2-hydroxy-3,5-dimethyltetrahydro-4H-pyran-4-one were consistent with those reported for the hemiacetal isolated from Siphonaria australis, and thus, prove the absolute and relative configuration of the natural product.

An efficient click synthesis of chalcones derivatized with two 1-(2-quinolon-4-yl)-1,2,3-triazoles

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Mohammed B. Alshammari ◽  
Ashraf A. Aly ◽  
Alan B. Brown ◽  
Md Afroz Bakht ◽  
Ahmed M. Shawky ◽  
...  
Keyword(s):  
Aldol Condensation ◽  
Aldol Reaction ◽  
Click Synthesis

Abstract Chalcones derivatized with 1-(2-quinolonyl)-1,2,3-triazoles were synthesized by reaction of 4-azido-2-quinolones with 1-phenyl-3-(4-propargyloxyphenyl)prop-2-en-1-one, or by aldol reaction of 4-{[1-(2-oxo-1,2-dihydroquinolin-4-yl)-1H-1,2,3-triazol-4-yl]methoxy}benzaldehydes with acetophenone. Whereas, chalcones bearing two 1-(2-quinolonyl)-1,2,3-triazoles were synthesized by reaction of 1,3-bis(4-propargyloxyphenyl)prop-2-en-1-one with 4-azido-2-quinolones, or by aldol condensation between 4-{4-[(4-acetylphenoxy)methyl]-1H-1,2,3-triazol-1-yl}quinolin-2(1H)-ones and 4-{[1-(2-oxo-1,2-dihydroquinolin-4-yl)-1H-1,2,3-triazol-4-yl]methoxy}benzaldehydes.

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