Regioselective Diboron-Mediated Semireduction of Terminal Allenes

Synthesis ◽  
2019 ◽  
Vol 51 (24) ◽  
pp. 4619-4624
Author(s):  
Ashley M. Gates ◽  
Webster L. Santos
Keyword(s):  
Double Bond ◽  
Palladium Catalyst ◽  
High Yield ◽  
Terminal Double Bond

A method for the regioselective reduction of the terminal double bond of 1,1-disubstituted allenes has been developed. In the presence of a palladium catalyst, tetrahydroxydiboron and stoichiometric water, allene semireduction proceeds in high yield to afford Z-alkenes selectively.

scholarly journals Synthesis of [1,4]Oxathiepino[5,6-b]quinolines via Base-Mediated Intramolecular Hydroalkoxylation

SynOpen ◽  
2022 ◽  
Vol 06 (01) ◽  
pp. 7-10
Author(s):  
Morteza Shiri ◽  
Maryam-Sadat Tonekaboni ◽  
Zahra Tanbakouchian ◽  
Soma Majedi
Keyword(s):  
Double Bond ◽  
Hydroxyl Group ◽  
High Yield ◽  
Formyl Group ◽  
Bond Yields ◽  
Terminal Double Bond ◽  
Subsequent Addition

AbstractA base-mediated intramolecular hydroalkoxylation that was used to prepare a series of seven-membered S,O-heterocycles is described. 2-Thiopropargyl-3-hydroxymethyl quinolines were prepared starting from 2-mercaptoquinoline-3-carbaldehydes, via S-propargylation and reduction of a formyl group. Interestingly, 2-mercaptopropargyl-3-hydroxymethyl quinolines were converted into the corresponding oxathiepinoquinolines in the presence of t-BuOK. It is proposed that the S-propargyl moiety, in the presence of base, is converted into its allenyl isomer; subsequent addition of a hydroxyl group to the terminal double bond yields the 3-methyl-5H-[1,4]oxathiepino[5,6-b]quinoline in good to high yield. Notably, the procedure is adaptable to the conversion of N-propargyl indole-2-methanol into the corresponding intramolecular hydroalkoxylation product.

scholarly journals Further Insight into Polycyclization Cascades of Acyclic Geranylfarnesol and its Acetate by Squalene-hopene Cyclase from Alicyclobacillus Acidocaldarius

2016 ◽  
Vol 11 (2) ◽  
pp. 1934578X1601100
Author(s):  
Jun Cheng ◽  
Chiaki Nakano ◽  
Guang Lu Shi ◽  
Tsutomu Hoshino
Keyword(s):  
Double Bond ◽  
Enzymatic Reaction ◽  
High Yield ◽  
Enzymatic Reactions ◽  
Terminal Double Bond ◽  
Tricyclic Compounds ◽  
Acetyl Group ◽  
Alicyclobacillus Acidocaldarius ◽  
Insight Into

The enzymatic reactions of geranylfarnesol (8) and its acetate 9, classified as sesterterpenes (C25), using squalene-hopene cyclase (SHC) were investigated. The enzymatic reaction of 8 afforded 6/6-fused bicyclic 20, 6/6/6-fused tricyclic 21, and 6/6/6/6-fused tetracyclic compounds 22 and 23 as the main products (35% yield), whereas that of 9 afforded two 6/6/6-fused tricyclic compounds 24 and 25 in a high yield (76.3%) and a small amount (5.0%) of 26 (the acetate of 22). A significantly higher conversion of 9 indicates that the arrangement of the substrate in the reaction cavity changed. The lipophilic nature and/or the bulkiness of the acetyl group may have changed its binding with SHC, thus placing the terminal double bond of 9 in the vicinity of the DXDD motif of SHC, which is responsible for the proton attack on the double bond to initiate the polycyclization reaction. The results obtained for 8 are different to some extent than those reported by Shinozaki et al. The products obtained in this study were deprotonated compounds; however, the products reported by Shinozaki et al. were hydroxylated compounds.

Addition of Tetrachloromethane to 1,5-Hexadiene

1992 ◽  
Vol 57 (2) ◽  
pp. 393-396 ◽  
Author(s):  
Martin Kotora ◽  
Milan Hájek
Keyword(s):  
Palladium Catalyst ◽  
Adduct Formation ◽  
High Yield ◽  
Reaction Conditions ◽  
Dibenzoyl Peroxide

The 2 : 1 adduct as the final product of the addition of tetrachloromethane to 1,5-hexadiene catalyzed by copper(I)-butylamine complex was obtained in high yield (96%) under mild reaction conditions. Predominant 1 : 1 adduct formation was observed in the presence of a palladium catalyst or dibenzoyl peroxide initiator.

scholarly journals Cathodic hydrodimerization of nitroolefins

2015 ◽  
Vol 11 ◽  
pp. 1163-1174 ◽  
Author(s):  
Michael Weßling ◽  
Hans J Schäfer
Keyword(s):  
Double Bond ◽  
Nitro Group ◽  
Bond Formation ◽  
Cathodic Reduction ◽  
High Yield ◽  
Easy Access ◽  
Electrolysis Cell ◽  
Aldehydes And Ketones ◽  
Nef Reaction

Nitroalkenes are easily accessible in high variety by condensation of aldehydes with aliphatic nitroalkanes. They belong to the group of activated alkenes that can be hydrodimerized by cathodic reduction. There are many olefins with different electron withdrawing groups used for cathodic hydrodimerization, but not much is known about the behaviour of the nitro group. Synthetic applications of this group could profit from the easy access to nitroolefins in large variety, the C–C bond formation with the introduction of two nitro groups in a 1,4-distance and the conversions of the nitro group by reduction to oximes and amines, the conversion into aldehydes and ketones via the Nef reaction and base catalyzed condensations at the acidic CH bond. Eight 1-aryl-2-nitro-1-propenes have been electrolyzed in an undivided electrolysis cell to afford 2,5-dinitro-3,4-diaryl hexanes in high yield. The 4-methoxy-, 4-trifluoromethyl-, 2-chloro- and 2,6-difluorophenyl group and furthermore the 2-furyl and 2-pyrrolyl group have been applied. The reaction is chemoselective as only the double bond but not the nitro group undergoes reaction, is regioselective as a ß,ß-coupling with regard to the nitro group and forms preferentially two out of six possible diastereomers as major products.

A simple method of isomerization of the terminal double bond in a terpene chain

1985 ◽  
Vol 50 (10) ◽  
pp. 2174-2178 ◽  
Author(s):  
Ludvík Streinz ◽  
Zdeněk Wimmer ◽  
Georgii K. Roshka ◽  
Raisa I. Ishchenko ◽  
Miroslav Romaňuk ◽  
...  
Keyword(s):  
Double Bond ◽  
Trifluoroacetic Acid ◽  
Main Part ◽  
Simple Method ◽  
Terminal Double Bond ◽  
Quadraspidiotus Perniciosus

The utilisability of the isomerization of the terminal double bond in terpenic compounds with trifluoroacetic acid was investigated. The results obtained were used in the synthesis of the main part of the pheromone of Quadraspidiotus perniciosus COMSTOCK, i.e. (2E)-3,7-dimethyl-2,7-octadien-1-yl propionate.

Extractives of Australian timbers. X. Autoxidation and other reactions of the conjugated side-chain of eberlin lactone. Isolation of a new isomer of ebelin lactone

1970 ◽  
Vol 23 (10) ◽  
pp. 2085 ◽  
Author(s):  
RA Eade ◽  
J Ellis ◽  
JS Shannon ◽  
HV Simes ◽  
JJH Simes
Keyword(s):  
Double Bond ◽  
Solid State ◽  
Osmium Tetroxide ◽  
Side Chain ◽  
Methyl Groups ◽  
Stepwise Manner ◽  
Terminal Double Bond ◽  
Conjugated Triene

The conjugated triene side-chain of ebelin lactone has been degraded in a stepwise manner using osmium tetroxide. A new isomer of ebelin lactone has been isolated from the sapogenin mixture and has been assigned the structure (9) in which the 25(26) double bond has the cis configuration. Autoxidation of ebelin lactone in the solid state yields a mixture from which three compounds have been isolated and identified; all three arise from oxidation of the side-chain at the terminal double bond and methyl groups.

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