An Atom-Economic and Stereospecific Access to Trisubstituted Olefins through Enyne Cross Metathesis Followed by 1,4-Hydrogenation

Synlett ◽  
2018 ◽  
Vol 29 (06) ◽  
pp. 785-792 ◽  
Author(s):  
Hans-Günther Schmalz ◽  
Friederike Ratsch
Keyword(s):  
Functional Group ◽  
Cross Metathesis ◽  
Broad Scope ◽  
Trisubstituted Olefins

The combination of intermolecular enyne cross metathesis and subsequent 1,4-hydrogenation opens a stereocontrolled and atom-economic access to trisubstituted olefins. By investigating different combinations of functionalized alkyne and alkene substrates, we found that the outcome (yield, E/Z ratio) of the Grubbs II-catalyzed enyne cross-metathesis step depends on the substrate’s structure, the amount of the alkene (used in excess), and the (optional) presence of ethylene. In any case, the 1,4-hydrogenation, catalyzed by 1,2-di­methoxybenzene-Cr(CO)3, proceeds stereospecifically to yield exclusively the E-products from both the E- and Z-1,3-diene intermediates obtained by metathesis. A rather broad scope and functional group compatibility of the method is demonstrated by means of 15 examples.

scholarly journals Relay Cross Metathesis for the Iterative Ascent of the Terpenoids

2019 ◽  
Author(s):  
Karim Bahou ◽  
D. Christopher Braddock ◽  
Adam G. Meyer ◽  
G. Paul Savage ◽  
Zhensheng Shi
Keyword(s):  
Natural Products ◽  
Functional Group ◽  
Building Blocks ◽  
Design And Implementation ◽  
Cross Metathesis ◽  
Naturally Occurring ◽  
Trisubstituted Olefins

<div>We report the design and implementation of a relay cross</div><div>metathesis (ReXM) reaction for the ascent of the terpenoids in an iterative protocol. The method features the reaction of naturally occurring terpenoid building blocks – with preexisting trisubstituted olefins – which combine to construct a new trisubstituted olefin resulting in a five-carbon unit homologation. Subsequent functional group manipulation allows for the method to be repeated in an</div><div>iterative fashion. The method is used for the synthesis of a diterpenebenzoate macrolide of biogenetic relevance to the bromophycolide family of natural products.</div>

scholarly journals Copper-Catalyzed Amination of Vinyl Azides to α-Ketoamides

SynOpen ◽  
2019 ◽  
Vol 03 (04) ◽  
pp. 91-95
Author(s):  
Yu Wang ◽  
Dongling Zhang ◽  
Kaining Zhang ◽  
Zhenhua Liu ◽  
Jing Lin ◽  
...  
Keyword(s):  
Benzoic Acid ◽  
Catalytic System ◽  
Functional Group ◽  
Efficient Approach ◽  
Broad Scope ◽  
Vinyl Azides ◽  
Oxidative Generation

An efficient approach for the amination of vinyl azides with N,N-dialkylacylamides has been developed. By using this protocol, structurally important α-ketoamides can be easily synthesized. The key to success is not only the introduction of a Cu(I)/oxygen catalytic system but also the utilization of t-BuOCl and benzoic acid as additives. The reaction is operationally simple, scalable, and displays broad scope and functional group tolerance. A possible mechanism involving copper-catalyzed oxidative generation of peroxide radicals is proposed.

Iron(III)/TEMPO-Catalyzed Synthesis of 2,5-Disubstituted 1,3,4-Oxadiazoles by Oxidative Cyclization under Mild Conditions

Synlett ◽  
2017 ◽  
Vol 28 (11) ◽  
pp. 1373-1377 ◽  
Author(s):  
Chengrong Ding ◽  
Guofu Zhang ◽  
Yidong Yu ◽  
Yiyong Zhao ◽  
Xiaoqiang Xie
Keyword(s):  
Functional Group ◽  
Oxidative Cyclization ◽  
Mild Conditions ◽  
Broad Scope ◽  
Oxadiazole Derivatives ◽  
High Yields

A simple and efficient cationic Fe(III)/TEMPO-catalyzed oxidative cyclization of aroyl hydrazones has been developed for the synthesis of 2,5-disubstituted 1,3,4-oxadiazole derivatives. The reaction offers a broad scope, good functional-group tolerance, and high yields under mild conditions in the presence of O2.

scholarly journals A Relay Strategy Actuates Pre-Existing Trisubstituted Olefins in Monoterpenoids to Form New Trisubstituted Olefins by Cross Metathesis

2019 ◽  
Author(s):  
Karim Bahou ◽  
D. Christopher Braddock ◽  
Adam G. Meyer ◽  
G. Paul Savage ◽  
Zhensheng Shi ◽  
...  
Keyword(s):  
Geometrical Isomer ◽  
Successful Implementation ◽  
Enantiomerically Pure ◽  
Cross Metathesis ◽  
Trisubstituted Olefins ◽  
The Cross ◽  
Trisubstituted Alkenes

<b><u>Abstract:</u></b> A retrosynthetic disconnection-reconnection analysis of epoxypolyenes – substrates that can undergo cyclization to podocarpane-type tricycles – reveals relay-actuated Δ<sup>6,7</sup>-functionalized monoterpenoid alcohols for ruthenium benzylidene catalyzed olefin cross metathesis with homoprenyl benzenes. Successful implementation of this approach provided several epoxypolyenes as expected (<i>E</i>:<i>Z</i>, ca. 2-3:1). The method is further generalized for the cross metathesis of pre-existing trisubstituted olefins in other relay-actuated Δ<sup>6,7</sup>-functionalized monoterpenoid alcohols with various other trisubstituted alkenes to form new trisubstituted olefins. Epoxypolyene cyclization of an enantiomerically pure, but geometrically impure, epoxypolyene substrate provides an enantiomerically pure, trans-fused, podocarpane-type tricycle (from the <i>E</i>-geometrical isomer).<br>

scholarly journals A Relay Strategy Actuates Pre-Existing Trisubstituted Olefins in Monoterpenoids for Cross-Metathesis with Trisubstituted Alkenes

2020 ◽  
Vol 85 (7) ◽  
pp. 4906-4917 ◽  
Author(s):  
Karim A. Bahou ◽  
D. Christopher Braddock ◽  
Adam G. Meyer ◽  
G. Paul Savage ◽  
Zhensheng Shi ◽  
...  
Keyword(s):  
Cross Metathesis ◽  
Trisubstituted Olefins ◽  
Trisubstituted Alkenes

scholarly journals Stable CAAC-based Ruthenium Complexes for Dynamic Olefin Metathesis Under Mild Conditions

2021 ◽  
Author(s):  
Oleksandr Kravchenko ◽  
Brian J.J. Timmer ◽  
Maurice Biedermann ◽  
Andrew Kentaro Inge ◽  
Olof Ramstrom
Keyword(s):  
Olefin Metathesis ◽  
High Stability ◽  
Room Temperature ◽  
Functional Group ◽  
Biologically Active ◽  
Dynamic Covalent Chemistry ◽  
Mild Conditions ◽  
Cross Metathesis ◽  
Potential Applications ◽  
Metathesis Catalysts

<p>A series of olefin metathesis catalysts bearing cyclic (alkyl)(amino)carbene (CAAC) ligands of varying size and steric demand has been synthesized and evaluated in ring-closing-, self-, and cross-metathesis reactions at room temperature. The catalysts were also probed for potential applications in dynamic covalent chemistry. The majority of the catalysts showed high stability, and remained active in the reaction mixtures for several days, including in methanol-based solutions. Higher temperatures could be used to control the reactivity towards sterically challenging substrates, enabling formation of tetrasubstituted olefins. The CAAC complexes exhibited remarkable functional group tolerance towards heteroaromatic and nucleophilic additives, making them potentially useful in the screening of biologically active compounds.</p>

Synthesis of α-deuterioalcohols by single-electron umpolung reductive deuteration of carbonyl using D2O as deuterium source

Synlett ◽  
2021 ◽  
Author(s):  
Hengzhao Li ◽  
Yuxia Hou ◽  
Zemin Lai ◽  
Lei ning ◽  
Ailing Li ◽  
...  
Keyword(s):  
Natural Products ◽  
Electron Donor ◽  
Potential Application ◽  
Functional Group ◽  
Chiral Center ◽  
Single Electron ◽  
Deuterium Incorporation ◽  
Broad Scope ◽  
High Yields

Deuterium incorporation can effectively stabilize the chiral centers of drug and agrochemical candidates that hampered by rapid in vivo racemization. In this work, the synthetically challenging chiral center deuteration of alcohols has been achieved via a single-electron umpolung reductive deuteration protocol using benign D2O as deuterium source and mild SmI2 as electron donor. The broad scope and excellent functional group tolerance of this method has been showcased by the synthesis of 43 respective α-deuterioalcohols in high yields and ≥98% deuterium incorporations. The potential application of this versatile method has been exemplified in the synthesis of 6 deuterated drug derivatives, 1 deuterated human hormone and 3 deuterated natural products. This method using D2O is greener and more efficient compared to traditional pyrophoric metal deuteride mediated reductive deuterations.

Catalyst-Controlled C–H Functionalization of Adamantanes using Selective H-Atom Transfer

2019 ◽  
Author(s):  
Hai-Bin Yang ◽  
Abigail Feceu ◽  
David Martin
Keyword(s):  
Functional Group ◽  
New Method ◽  
Alkylation Reaction ◽  
Atom Transfer ◽  
Broad Scope ◽  
Direct Functionalization ◽  
Photochemical Systems ◽  
Substrate Competition

<p>A new method for the direct functionalization of diamondoids has been developed using photoredox and H-atom transfer catalysis. This C–H alkylation reaction has excellent chemoselectivity for the strong 3º C–H bonds of adamantanes in polyfunctional molecules. In substrate competition reactions, a reversal in selectivity is observed for the new H-atom transfer catalyst reported here when compared to six known photochemical systems. Derivatization of a broad scope of diamondoids and adamantane-containing drugs highlights the versatility and functional group tolerance of this C–H functionalization strategy.</p>

Catalyst-Controlled C–H Functionalization of Adamantanes using Selective H-Atom Transfer

2019 ◽  
Author(s):  
Hai-Bin Yang ◽  
Abigail Feceu ◽  
David Martin
Keyword(s):  
Functional Group ◽  
New Method ◽  
Alkylation Reaction ◽  
Atom Transfer ◽  
Broad Scope ◽  
Direct Functionalization ◽  
Photochemical Systems ◽  
Substrate Competition

<p>A new method for the direct functionalization of diamondoids has been developed using photoredox and H-atom transfer catalysis. This C–H alkylation reaction has excellent chemoselectivity for the strong 3º C–H bonds of adamantanes in polyfunctional molecules. In substrate competition reactions, a reversal in selectivity is observed for the new H-atom transfer catalyst reported here when compared to six known photochemical systems. Derivatization of a broad scope of diamondoids and adamantane-containing drugs highlights the versatility and functional group tolerance of this C–H functionalization strategy.</p>

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