Improved Synthesis of Long Chain 1-Alkynes and Terminal Alkadiynes

Beckmann, Wolfgang; Doerjer, Gerhard; Logemann, Enno; Merkel, Christine; Schill, Gottfried; Zürcher, Clemens

doi:10.1055/s-1975-23780

Cited by 38 publications

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“…1,6-Hexanediol was converted to 6-iodo-1-hexanol via refluxing the diol in a mixture of octane and 51% aqueous HI. After purification, the alcohol was protected via reaction with dihydropyran 14 and reacted with acetylene according to the method of Beckmann et al 15 to form 1-tetrahydropyranyloxy-7octyne. This terminal alkyne was alkylated with 6-chloro-1-iodohexane as described by Schwarz et al 16 and Gensler et al 17 to give 1-tetrahydropyranyloxy-14-chloro-7-tetradecyne.…”

Section: Methodsmentioning

confidence: 99%

Modulation of Electronic Coupling through Self-Assembled Monolayers via Internal Chemical Modification

et al. 1996

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Self-assembled monolayers of ω-hydroxyalkanethiols at Au electrodes are used to probe the structural dependence of long-range electron transfer. The electron transfer rates for ferricyanide and osmium(III) tris(bipyridyl) are measured at Au electrodes coated with self-assembled monolayers of HO(CH 2 ) n -X-(CH 2 ) m SH where X denotes an ether, olefin, or alkyne function. Each of these modifications decreases the electronic coupling across the monolayers. Ab initio calculations of the neutral diradical splitting energies for modified and unmodified alkanes correctly predict these decreases in electronic coupling.

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Section: Methodsmentioning

confidence: 99%

Modulation of Electronic Coupling through Self-Assembled Monolayers via Internal Chemical Modification

et al. 1996

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“…General Procedure for Preparation of Starting Enynes. To a solution of the alkyne (11 mmol) in 15 mL of dry THF and 10 mL of HMPA was added dropwise n -BuLi (13 mmol) at −78 °C.…”

Section: Methodsmentioning

confidence: 99%

Bicyclization of Enynes Using the Cp₂TiCl₂−Mg−BTC System: A Practical Method to Bicyclic Cyclopentenones

1998

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Bicyclic titanacycles 2 generated with the Cp 2 TiCl 2 -Mg-P(OEt) 3 system can be trapped with bis-(trichloromethyl) carbonate (BTC) to give bicyclic cyclopentenones 3 in good yields. The titanacycle 2m was isolated and well-identified. Bicyclization of enynes containing 1,2-disubstituted olefin by this method gave good results with excellent stereoselectivity.a Method A: CO, M ) Ti, Zr. Method B: R3SiCN, then HOAc or CuSO4, M ) Ti.

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“…The top half of Scheme shows Schill's access to the key building blocks of his catenane‐from‐rotaxane endeavor: They were the ω‐bromo‐C 13 ‐alkyne 55 (usage: Scheme ), the ω‐(trityloxy)‐C 11 ‐bromide 56 (usage: Scheme ), and the C 28 ‐cycloalkane 65 (usage: Scheme ). The ω‐bromo‐C 13 ‐alkyne 55 was derived from the ω‐bromo‐C 11 ‐alcohol 28 by adding it to dihydropyran, introducing lithium acetylide, cleaving the THP ether, and substituting OH by Br . The ω‐(trityloxy)‐C 11 ‐bromide 56 stemmed from the ω‐bromo‐C 11 ‐alcohol 28 and trityl chloride .…”

Section: Catenanes From Freiburg and A Rotaxane → Catenane Conversionmentioning

confidence: 99%

“…According to Scheme the synthesis of what may have been the knotane‐precursor rac ‐ dia ‐ iso ‐ 123 incorporated five building blocks: cyclohexanone ( 116 ) and catechol ( 117 ) in step 1, the bromide 53 (itself prepared from the ω‐bromoalcohol 28 in the 1 step specified in Scheme ) in step 2, the bromoalkyne 54 (prepared from the same ω‐bromoalcohol 28 in the 2 steps, detailed in Scheme ) in step 6, and the dichloroketone 30 (which, too, stemmed from the ω‐bromoalcohol 28 and from the 7 transformations shown in Scheme ) in step 11 . Altogether, steps 1–4 and 5–11 of Scheme gave the bisketal 121 in 20 % overall yield.…”

Section: Schill's 1979 Attempt To Synthesize a Molecular Knotmentioning

confidence: 99%

Pioneering Work on Catenanes, Rotaxanes, and a Knotane in the University of Freiburg 1958–1988

Brückner

2019

Eur J Org Chem

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Research at the University of Freiburg is summarized which aimed at realizing catenanes, rotaxanes, and a molecular knot from 61–62 until 41 years ago. Taking a fresh view at ansa‐compounds – distinct from those in which he had been interested for other reasons before – Arthur Lüttringhaus began to tackle syntheses of catenanes in 1957. The first isolation of a pure catenane (37) succeeded in 1964 jointly with Gottfried Schill. Most of the progress made in the sequel was due to Schill alone or achieved under his direction; in addition, a few follow‐up studies were published without Schill or Lüttringhaus being their authors. The major feats of these endeavors were the syntheses of the following molecules: (1) the first catenanes (38 – de‐acetyl‐41, 74) without a ring in any constituent (this feature makes them unique till today; the catenane 74 holds the additional record of being the only all‐hydrocarbon catenane till now); the first [3]catenanes at all (obtained as a mixture of constitutional isomers C2v‐97 and C2h‐97); the first [3]catenanes exhibiting topological isomerism (89, iso‐89, and neo‐iso‐89); the rotaxanes 70 [which had the design peculiarity of being convertible into a catenane (74)], 113 (Schill's #1‐rotaxane), and 115; the pre‐knotane rac‐dia‐iso‐123 [provided it was obtained and not (only) its topological isomer dia‐iso‐123]. – For due perspectives, pertinent studies of third parties are included, too: 1) Wasserman's reports on the isolation of the catenane 8 are analyzed in great detail; the conclusion is that the identity of 8 was never established. 2) Schill's oscillating rotaxane 70 from 1988, which is subject to a reversible and non‐degenerate ring migration (→ iso‐70), is supplemented by Stoddart's much faster oscillating rotaxane 71 from 1991, which undergoes a reversible and degenerate ring migration (→ 71 instead of → iso‐71) and was dubbed “molecular shuttle”. 3) The first [3]catenanes from the groups of Schill (97; 1969), Sauvage (98 and 99; 1985), and Stoddart (100–102; 1991) are juxtaposed. 4) The Harrisons' synthesis of the rotaxane 106 by a most noteworthy solid‐phase approach (1967) is recalled in the context of Schill's synthesis of the rotaxane 113 (1967 or 1969). 5) Attempts at threading α‐cyclodextrin by long‐chain 1,ω‐dithiols (→ 130) and ring‐closing the latter oxidatively for obtaining catenated disulfides failed in Lüttringhaus' 1957/1958 studies; in contrast, Stoddart's threading permethyl‐β‐cyclodextrin (133) by the long‐chain 1,ω‐diamine 132 and ring‐closing the latter by a double condensation with terephthaloyl dichloride was successful by providing 3 % of the catenated bislactame 134 in 1993. The concluding section characterizes the synthetic strategies towards catenanes and rotaxanes developed in Freiburg as “template‐based”. This differs from the Nobel Prize Committee's assessment.

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Improved Synthesis of Long Chain 1-Alkynes and Terminal Alkadiynes

Cited by 38 publications

References 0 publications

Modulation of Electronic Coupling through Self-Assembled Monolayers via Internal Chemical Modification

Modulation of Electronic Coupling through Self-Assembled Monolayers via Internal Chemical Modification

Bicyclization of Enynes Using the Cp₂TiCl₂−Mg−BTC System: A Practical Method to Bicyclic Cyclopentenones

Pioneering Work on Catenanes, Rotaxanes, and a Knotane in the University of Freiburg 1958–1988

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Improved Synthesis of Long Chain 1-Alkynes and Terminal Alkadiynes

Cited by 38 publications

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Modulation of Electronic Coupling through Self-Assembled Monolayers via Internal Chemical Modification

Modulation of Electronic Coupling through Self-Assembled Monolayers via Internal Chemical Modification

Bicyclization of Enynes Using the Cp2TiCl2−Mg−BTC System: A Practical Method to Bicyclic Cyclopentenones

Pioneering Work on Catenanes, Rotaxanes, and a Knotane in the University of Freiburg 1958–1988

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Bicyclization of Enynes Using the Cp₂TiCl₂−Mg−BTC System: A Practical Method to Bicyclic Cyclopentenones