A Congested <i>in,in</i>-Diphosphine

Zong, Jie; Mague, Joel T.; Kraml, Christina M.; Pascal, Robert A.

doi:10.1021/ol400728m

Cited by 17 publications

(23 citation statements)

References 17 publications

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“…14), and the molecule lies on a general position. It proved to be the in,in ‐isomer, and, as expected, it adopts a very nearly C 3 ‐symmetric conformation, as is invariably the case for the in,in ‐cyclophanes that we have previously characterized . The structure is illustrated in Figure .…”

Section: Resultssupporting

confidence: 63%

“…A solution of tris(2‐mercaptophenyl)phosphine ( 4 ) and tris(3‐bromopropyl)methane[4d] ( 5 ) (0.9 m m each) in refluxing 2:1 benzene/ethanol was treated with KOH. After purification by repeated preparative TLC, the cyclophanes 1 , 2 , and 3 were isolated in approximately 7 %, 5 %, and 10 % yields, respectively.…”

Section: Resultsmentioning

confidence: 99%

“…In every case, we were pursuing the synthesis of small, strained in ‐cyclophanes or in,in ‐cyclophanes, and in almost every case, the desired in ‐isomers were obtained. Indeed, in only three macrocyclization reactions did we observe out ‐ or in,out ‐cyclophanes,[3g], [4c] but these involved attempts to put methyls or larger groups into the central cavities of the cyclophanes. (Of course, we only rarely reported reactions that gave no well‐characterized cyclophanes.)…”

Section: Introductionmentioning

confidence: 99%

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Multiple Isomers of a Small, Strained Phosphaphane

2018

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Three cyclophanes with the formula (C28H31PS3)n, where n = 1 or 2, were isolated from the base‐promoted macrocyclization of tris(2‐mercaptophenyl)phosphine (4) and tris(3‐bromopropyl)methane (5). Spectroscopic and X‐ray analysis showed them to be the in,in‐isomer 1, the in,out‐isomer 2, and a dimeric in,out,in,out‐isomer 3. Compounds 1 and 3 display approximately C3‐symmetric and Ci‐symmetric structures, respectively, in the crystal, but compound 2 adopts two distinct low‐symmetry conformations in the solid state. In each case, the observed structures correspond to the lowest energy conformations of their respective isomers as calculated at the B3PW91/6‐31G(d) level of theory. The in,in‐isomer 1 displays a close contact between the phosphine in‐lone pair and the in‐methine group, with through‐space spin–spin coupling constants of JPH = 9 Hz and JPC = 24 Hz, the latter of which appears to be the largest reported phosphorus‐carbon through‐space coupling constant.

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Section: Resultssupporting

confidence: 63%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Multiple Isomers of a Small, Strained Phosphaphane

2018

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“…Now the in , out isomer exhibited one 31 P NMR signal, which was indicative of a low barrier for homeomorphic isomerization. Reductions gave the analogous dibridgehead diphosphines and phosphine/BH 3 adducts, and related dibridgehead diphosphites and diphosphates were also prepared …”

Section: Discussionmentioning

confidence: 99%

A Nontemplated Route to Macrocyclic Dibridgehead Diphosphorus Compounds: Crystallographic Characterization of a “Crossed‐Chain” Variant of in/out Stereoisomers

Kharel

Jia

Bhuvanesh

et al. 2018

Chemistry An Asian Journal

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Reactions of (O=)PH(OCH CH ) and BrMg(CH ) CH=CH (4.9-3.2 equiv; m=4 (a), 5 (b), 6 (c)) give the dialkylphosphine oxides (O=)PH[(CH ) CH=CH ] (2 a-c; 77-81 % after workup), which are treated with NaH and then α,ω-dibromides Br(CH ) Br (0.49-0.32 equiv; n=8 (a'), 10 (b'), 12 (c'), 14 (d')) to yield the bis(trialkylphosphine oxides) [H C=CH(CH ) ] P(=O)(CH ) (O=)P[(CH ) CH=CH ] (3 ab', 3 bc', 3 cd', 3 ca'; 79-84 %). Reactions of 3 bc' and 3 ca' with Grubbs' first-generation catalyst and then H /PtO afford the dibridgehead diphosphine dioxides (4 bc', 4 ca'; 14-19 %, n'=2m+2); P NMR spectra show two stereoisomeric species (ca. 70:30). Crystal structures of two isomers of the latter are obtained, out,out-4 ca' and a conformer ofin,out-4 ca' that features crossed chains, such that the (O=)P vectors appear out,out. Whereas 4 bc' resists crystallization, a byproduct derived from an alternative metathesis mode, (CH ) P(=O)(CH ) (O=)P(CH ) , as well as 3 ab' and 3 bc', are structurally characterized. The efficiencies of other routes to dibridgehead diphosphorus compounds are compared.

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“…Over the last 25 years, we have prepared numerous triarylelement‐capped in ‐cyclophanes (such as compounds 1 – 3 ) and, more recently, a series of related in,in ‐cyclophanes (e.g. 4 ).…”

Section: Introductionmentioning

confidence: 99%

Chiral Polyaryl Cyclophanes

et al. 2017

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A series of propeller‐shaped, C3‐symmetric cyclophanes have been synthesized by the macrocyclization of 1,3,5‐trimercaptobenzene (12) with either a tris[o‐(halomethyl)aryl]phosphine (e.g. 11) or a tris[o‐(halomethyl)aryl]benzene (e.g. 24). Two phosphine‐capped cyclophanes (5 and 6) were prepared in this way; they proved to be configurationally stable, and both were resolved into pure enantiomers by supercritical fluid chromatography on chiral supports. Compound 6, in particular, displayed a large specific rotation ([α]D ≈ 800) and strong circular dichroism. The one triarylbenzene‐capped cyclophane (9) that was made possessed a modest barrier to racemization (ΔGrac‡ = 15.7 kcal/mol). Computational studies of the trends in optical rotation for this class of compounds as well as the pathway for the racemization of 9 are also reported.

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A Congested in,in-Diphosphine

Cited by 17 publications

References 17 publications

Multiple Isomers of a Small, Strained Phosphaphane

Multiple Isomers of a Small, Strained Phosphaphane

A Nontemplated Route to Macrocyclic Dibridgehead Diphosphorus Compounds: Crystallographic Characterization of a “Crossed‐Chain” Variant of in/out Stereoisomers

Chiral Polyaryl Cyclophanes

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