Dicarboxylates of 3-Methylidene-β-lactams: Addition Reactions to the Exocyclic Double Bond, Formation of Spiro-β-lactams, and Reductive Ring Opening by Hydrazines

1993 ◽  
Vol 76 (8) ◽  
pp. 2958-2968 ◽  
Author(s):  
Susanne Gürtler ◽  
Michael Johner ◽  
Sabine Ruf ◽  
Hans-Hartwig Otto
Keyword(s):  
Double Bond ◽  
Ring Opening ◽  
Bond Formation ◽  
Exocyclic Double Bond ◽  
Addition Reactions

A P–H functionalized Al/P-based frustrated Lewis pair – hydrophosphination of nitriles, ring opening with cyclopropenones and evidence of PC double bond formation

2018 ◽  
Vol 47 (25) ◽  
pp. 8402-8417 ◽  
Author(s):  
Lukas Keweloh ◽  
Niklas Aders ◽  
Alexander Hepp ◽  
Damian Pleschka ◽  
Ernst-Ulrich Würthwein ◽  
...  
Keyword(s):  
Double Bond ◽  
Ring Opening ◽  
Bond Formation ◽  
Frustrated Lewis Pair

A P–H functionalized FLP reacted with RX-CN by hydrophosphination. Ring opening by treatment with cyclopropenthione resulted in PC bond formation.

scholarly journals Chemoselective Ring-Opening Polymerization of Bio-Renewable α-Methylene-γ-Butyrolactone via an Organophosphazene/urea Binary Synergistic Catalytic System Toward a Sustainable Polyester

2020 ◽  
Author(s):  
Yong Shen ◽  
Wei Xiong ◽  
YongZheng Li ◽  
ZhiChao Zhao ◽  
Hua Lu ◽  
...  
Keyword(s):  
Double Bond ◽  
Catalytic System ◽  
Low Temperatures ◽  
Ring Opening ◽  
Theoretical Calculations ◽  
Unsaturated Polyester ◽  
Ring Opening Polymerization ◽  
Membered Ring ◽  
Exocyclic Double Bond ◽  
Binary Catalyst

Despite the great potential of bio-renewable a-methylene-<a></a><a></a><a>g-butyrolactone</a> (MBL) to produce functional recyclable polyester, the ring-opening polymerization (ROP) of MBL remains as a challenge due to the competing polymerization of the highly reactive exocyclic double bond and the low strained five membered ring. In this contribution, we present the first organocatalytic chemoselective ROP of MBL to exclusively produce recyclable unsaturated polyester by utilizing a phosphazene base/urea binary catalyst. We show that delicate chemoselectivity can be realized by controlling the temperature and using selected urea catalysts. Experimental and theoretical calculations provide mechanistic insights and indicate that the kinetically controlled ROP pathway is favored by using urea with stronger acidity at low temperatures.

Genome mining of cryptic tetronate natural products from a PKS-NRPS encoding gene cluster in Trichoderma harzianum t-22

2021 ◽  
Vol 19 (9) ◽  
pp. 1985-1990
Author(s):  
Yiguang Zhu ◽  
Junfeng Wang ◽  
Pengyun Mou ◽  
Yan Yan ◽  
Mengbin Chen ◽  
...  
Keyword(s):  
Natural Products ◽  
Double Bond ◽  
Gene Cluster ◽  
Trichoderma Harzianum ◽  
Bond Formation ◽  
Genome Mining ◽  
Exocyclic Double Bond ◽  
Encoding Gene

The gene cluster of trihazones was identified from Trichoderma harzianum t-22 and heterologously activated in Aspergillus nidualns. The α-KG dependent dioxygenase ThnC was confirmed to catalyze exocyclic double bond formation.

scholarly journals Chemoselective Ring-Opening Polymerization of Bio-Renewable α-Methylene-γ-Butyrolactone via an Organophosphazene/urea Binary Synergistic Catalytic System Toward a Sustainable Polyester

2020 ◽  
Author(s):  
Yong Shen ◽  
Wei Xiong ◽  
YongZheng Li ◽  
ZhiChao Zhao ◽  
Hua Lu ◽  
...  
Keyword(s):  
Double Bond ◽  
Catalytic System ◽  
Low Temperatures ◽  
Ring Opening ◽  
Theoretical Calculations ◽  
Unsaturated Polyester ◽  
Ring Opening Polymerization ◽  
Membered Ring ◽  
Exocyclic Double Bond ◽  
Binary Catalyst

Despite the great potential of bio-renewable a-methylene-<a></a><a></a><a>g-butyrolactone</a> (MBL) to produce functional recyclable polyester, the ring-opening polymerization (ROP) of MBL remains as a challenge due to the competing polymerization of the highly reactive exocyclic double bond and the low strained five membered ring. In this contribution, we present the first organocatalytic chemoselective ROP of MBL to exclusively produce recyclable unsaturated polyester by utilizing a phosphazene base/urea binary catalyst. We show that delicate chemoselectivity can be realized by controlling the temperature and using selected urea catalysts. Experimental and theoretical calculations provide mechanistic insights and indicate that the kinetically controlled ROP pathway is favored by using urea with stronger acidity at low temperatures.

Reactions of 4-Pyrones with Azomethine Ylides as a Chemo­selective Method for the Construction of Multisubstituted Pyrano[2,3-c]pyrrolidines

Synthesis ◽  
2021 ◽  
Author(s):  
Dmitrii L. Obydennov ◽  
Vyacheslav D. Steben’kov ◽  
Konstantin L. Obydennov ◽  
Sergey A. Usachev ◽  
Vladimir S. Moshkin ◽  
...  
Keyword(s):  
Double Bond ◽  
Ring Opening ◽  
Azomethine Ylides ◽  
Azomethine Ylide ◽  
Dipolar Cycloaddition ◽  
Computational Studies ◽  
Carbon Double Bond ◽  
Reactivity Indexes ◽  
Reaction Proceeds

Abstract4-Pyrones bearing electron-donating and electron-withdrawing groups react with nonstabilized azomethine ylides to form pyrano[2,3-c]pyrrolidines in moderate to good yields. The reaction proceeds chemoselectively as a 1,3-dipolar cycloaddition of the azomethine ylide at the carbon–carbon double bond of the pyrone activated by the electron-withdrawing substituent. The reactivity of 4-pyrones toward azomethine ylides was rationalized by computational studies with the use of reactivity indexes. The pyrano[2,3-c]pyrrolidine moiety could be modified, for example by a ring-opening transformation under the action of hydrazine to provide pyrazolyl-substituted pyrrolidines.

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