Three-Component [1+1+1] Cyclopropanation with Ruthenium(II)

2018 ◽  
Author(s):  
Tanner C. Jankins ◽  
Robert R. Fayzullin ◽  
Eugene Khaskin
Keyword(s):  
Quaternary Carbon ◽  
Poor Control ◽  
One Step ◽  
Synthetic Routes ◽  
Mechanistic Investigations ◽  
Chiral Centers ◽  
Metal Catalyzed ◽  
The Right ◽  
Substituted Cyclopropanes

We report a one-step, Ru(II)-catalyzed cyclopropanation reaction that is conceptually different from the previously reported protocols that include Corey-Chaykovsky, Simmons-Smith, and metal catalyzed carbene attack on olefins. Under the current protocol, various alcohols are transformed into sulfone substituted cyclopropanes with excellent isolated yields and diastereoselectivities. This new reaction forms highly congested cyclopropane products with three new C–C bonds, three or two new chiral centers and one new quaternary carbon center. 22 examples of isolated substrates are given. Previously reported synthetic routes for similar substrates are all multi-step, linear routes that proceed with overall low yields and poor control of stereochemistry. Experimental mechanistic investigations suggest initial metal-catalyzed dehydrogenation of the alcohol substrate and catalyst independent stepwise attack of two equivalents of sulfone on the aldehyde under basic conditions. While the Ru(II) is only responsible for the initial dehydrogenation step, the rate of aldehyde formation is crucial to maintaining the right balance of intermediates needed to afford the cyclopropane product.

Three-Component [1+1+1] Cyclopropanation with Ruthenium(II)

2018 ◽  
Author(s):  
Tanner C. Jankins ◽  
Robert R. Fayzullin ◽  
Eugene Khaskin
Keyword(s):  
Quaternary Carbon ◽  
Poor Control ◽  
One Step ◽  
Synthetic Routes ◽  
Mechanistic Investigations ◽  
Chiral Centers ◽  
Metal Catalyzed ◽  
The Right ◽  
Substituted Cyclopropanes

We report a one-step, Ru(II)-catalyzed cyclopropanation reaction that is conceptually different from the previously reported protocols that include Corey-Chaykovsky, Simmons-Smith, and metal catalyzed carbene attack on olefins. Under the current protocol, various alcohols are transformed into sulfone substituted cyclopropanes with excellent isolated yields and diastereoselectivities. This new reaction forms highly congested cyclopropane products with three new C–C bonds, three or two new chiral centers and one new quaternary carbon center. 22 examples of isolated substrates are given. Previously reported synthetic routes for similar substrates are all multi-step, linear routes that proceed with overall low yields and poor control of stereochemistry. Experimental mechanistic investigations suggest initial metal-catalyzed dehydrogenation of the alcohol substrate and catalyst independent stepwise attack of two equivalents of sulfone on the aldehyde under basic conditions. While the Ru(II) is only responsible for the initial dehydrogenation step, the rate of aldehyde formation is crucial to maintaining the right balance of intermediates needed to afford the cyclopropane product.

Three-Component [1+1+1] Cyclopropanation with Ruthenium(II)

2018 ◽  
Author(s):  
Tanner C. Jankins ◽  
Robert R. Fayzullin ◽  
Eugene Khaskin
Keyword(s):  
Quaternary Carbon ◽  
Poor Control ◽  
One Step ◽  
Synthetic Routes ◽  
Mechanistic Investigations ◽  
Chiral Centers ◽  
Metal Catalyzed ◽  
The Right ◽  
Substituted Cyclopropanes

We report a one-step, Ru(II)-catalyzed cyclopropanation reaction that is conceptually different from the previously reported protocols that include Corey-Chaykovsky, Simmons-Smith, and metal catalyzed carbene attack on olefins. Under the current protocol, various alcohols are transformed into sulfone substituted cyclopropanes with excellent isolated yields and diastereoselectivities. This new reaction forms highly congested cyclopropane products with three new C–C bonds, three or two new chiral centers and one new quaternary carbon center. 22 examples of isolated substrates are given. Previously reported synthetic routes for similar substrates are all multi-step, linear routes that proceed with overall low yields and poor control of stereochemistry. Experimental mechanistic investigations suggest initial metal-catalyzed dehydrogenation of the alcohol substrate and catalyst independent stepwise attack of two equivalents of sulfone on the aldehyde under basic conditions. While the Ru(II) is only responsible for the initial dehydrogenation step, the rate of aldehyde formation is crucial to maintaining the right balance of intermediates needed to afford the cyclopropane product.

Enantioselective Multi-Component Cyclopropane Synthesis Enabled by Cu-Catalyzed Cyclopropene Carbometallation with Organoboron Reagent

2018 ◽  
Author(s):  
Zhanyu Li ◽  
Mengru Zhang ◽  
Yu Zhang ◽  
Shuang Liu ◽  
Jinbo Zhao ◽  
...  
Keyword(s):  
Carbon Source ◽  
Stereoselective Synthesis ◽  
Organometallic Reagents ◽  
Preliminary Results ◽  
Quaternary Center ◽  
Chiral Centers ◽  
Substituted Cyclopropanes ◽  
Proof Of Principle

Deployment of organoboron in lieu of the strongly basic <br>organometallic reagents as carbon source in Cu-catalyzed <br>cyclopropene carbometallation opens unprecedented three-<br>component reactivity for stereoselective synthesis of poly-substituted cyclopropanes. A proof-of-principle demonstration of this novel carbometallation strategy is presented herein for a highly convergent access to poly-substituted aminocyclopropane framework via <br>carboamination. Preliminary results on asymmetric desymmetrization with commercial bisphosphine ligands attained high levels of enantioselection, offering a straightforward access to enantioenriched aminocyclopropanes bearing all-three chiral centers, including an all-carbon quaternary center. This strategy may underpin a host of novel synthetic protocols for poly-substituted cyclopropanes. <br>

scholarly journals Surgical treatment for common hepatic aneurysm. Original one-step technique

Open Medicine ◽  
2020 ◽  
Vol 15 (1) ◽  
pp. 898-904
Author(s):  
Bruno Amato ◽  
Renato Patrone ◽  
Gennaro Quarto ◽  
Rita Compagna ◽  
Roberto Cirocchi ◽  
...  
Keyword(s):  
Surgical Treatment ◽  
Hepatic Artery ◽  
Distal Part ◽  
Intraoperative Ultrasound ◽  
Section Area ◽  
One Step ◽  
A New Technique ◽  
Open Surgical Treatment ◽  
The Right ◽  
Vascular Stapler

AbstractIntroductionHepatic artery aneurysms are rare, and their treatment represents a challenge for the surgeons.Materials and methodsA new technique is presented for common hepatic artery (CHA) aneurysm: it requires minimal vascular surgical dissection and only one linear vascular stapler is applied at the bottom of aneurysm. Aneurysm exclusion is easily obtained, which allowed retrograde thrombosis. Liver blood supply is ensured to the right and left hepatic artery, through the gastroduodenal artery, and can be previously monitored, with temporary clamping of the section area, by visual control, enzyme evaluation and intraoperative ultrasound examination. We reported an open surgical treatment, with simultaneous removal of hepatic and adrenal metastases, secondary to colon cancer.ResultsThe duration of vascular surgery was 30 min and did not involve complications. Postoperative controls confirmed the efficacy of the procedure.DiscussionThis original technique can be added to the various open and endovascular techniques so far described for the treatment of a CHA aneurysm. It is advisable as open surgery, mostly in case of associated pathologies.ConclusionsThe authors believe that this “one shot” technique by vascular staple of the distal part of CHA is minimally invasive and effective to obtain the exclusion of the aneurysm.

Mandatory desexing of dogs: one step in the right direction to reduce the risk of dog bite? A systematic review

2017 ◽  
Vol 23 (3) ◽  
pp. 212-218 ◽  
Author(s):  
Katina D'Onise ◽  
Susan Hazel ◽  
Charles Caraguel
Keyword(s):  
Systematic Review ◽  
Dog Bite ◽  
One Step ◽  
The Right

Single-shelf library-type Markov chains with infinitely many books

1977 ◽  
Vol 14 (02) ◽  
pp. 298-308 ◽  
Author(s):  
Peter R. Nelson
Keyword(s):  
Markov Chain ◽  
Markov Chains ◽  
Transition Probabilities ◽  
Natural Order ◽  
Order Book ◽  
Exit Boundary ◽  
One Step ◽  
Step Transition ◽  
The Right ◽  
Positive Recurrent

In a single-shelf library having infinitely many books B 1 , B 2 , …, the probability of selecting each book is assumed known. Books are removed one at a time and replaced in position k prior to the next removal. Books are moved either to the right or the left as is necessary to vacate position k. Those arrangements of books where after some finite position all the books are in natural order (book i occupies position i) are considered as states in an infinite Markov chain. When k &gt; 1, we show that the chain can never be positive recurrent. When k = 1, we find the limits of ratios of one-step transition probabilities; and when k = 1 and the chain is transient, we find the Martin exit boundary.

Synthesis of Chlorinated Arenes and Hetarenes by One-Pot Cyclizations of 1,3-Bis-silyl Enol Ethers

Synlett ◽  
2019 ◽  
Vol 30 (06) ◽  
pp. 665-673 ◽  
Author(s):  
Peter Langer ◽  
Zahid Hassan
Keyword(s):  
Cost Effective ◽  
Coupling Reactions ◽  
One Pot ◽  
Enol Ethers ◽  
Silyl Enol Ethers ◽  
Cross Coupling Reactions ◽  
Silyl Enol Ether ◽  
Synthetic Routes ◽  
Metal Catalyzed ◽  
High Level

This account describes our recent findings and progress in synthesizing chlorinated arenes and hetarenes by one-pot cyclizations of 1,3-bis-silyl enol ether derivatives. These reactions allow for the preparation of highly functionalized products with a high level of regioselectivity. The synthetic routes are cost-effective avoiding additional functionalization steps. The products are difficult to be accessed by other methods. The chlorine atom is of relevance in medicinal and agriculture chemistry. In addition, it allows further functionalizations by transition-metal-catalyzed cross-coupling reactions.1 Introduction2 Cyclizations of 2-Chloro-1,3-bis(silyloxy)-1,3-butadienes2.1 3,5-Dihydroxychlorophthalates2.2 2,4-Dihydroxy-homochlorophthalates2.3 2-(Arylsulfonyl)chloropyridines2.4 1-Azaxanthones3 Cyclizations of 4-Chloro-1,3-bis(trimethylsilyloxy)-1,3-butadienes3.1 3-Chlorosalicylates3.2 Functionalized Chlorobiaryls3.3 3-Chloro-5-(2-chloroethyl)-salicylates3.4 2,4-Dihydroxychlorobenzophenones4 Cyclizations of 2-Chloro-3-(silyloxy)-2-en-1-ones4.1 Functionalized Chlorophenols4.2 Functionalized Chlorinated Biaryls and Chlorofluorenones4.3 Functionalized Chlorochromenones4.4 Functionalized 3-(Methylthio)chlorophenols4.5 Functionalized 3-Chloromethylphenols5 Conclusions6 List of Abbreviations

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