Carbene, V. 7‐Phosphono‐7‐aryl‐norcaradiene

Abstract

Die Bestrahlung der Phosphonodiazomethane 4a-d (dargestellt durch Eamford-SfevensReaktion) und 6 (dargestellt durch Diazogruppen-Ubertragung) in Benzol liefert 7-Phosphono-7-aryl-norcaradiene (7a -e) sowie 3.8-Bis-phosphono-3.8-diaryl-tricyclo[5.1.0.02~~]octene-(5) (9a-e). Fur 7 a wird ein temperaturabhangiges Valenzisomerie-Gleichgewicht gemla 7 Z? 8 NMR-spektroskopisch nachgewiesen. Wahrend p-Xylol mit photolytisch erzeugtem Dimethylphosphono-phenyl-carben ausschliealich H-Abstraktionsprodukte liefert (16,17,18), reagieren p-Dichlor-und p-Dimethoxybenzol mit Phosphono-aryl-carbenen zu den 2.5-Dichlor-und 2.5-Dimethoxy-norcaradienen 19a-d. Sie Carbenes, v2) 7-Phosphono-7-arylnorcaradienesThe photolysis of the phosphonodiazomethanes 4a -d (prepared by Bumford-Stevens reaction) and 6 (prepared by diazo group transfer) in benzene yields 7-phosphono-7-arylnorcaradienes (7a-e) as well as 3.8-diaryl-3.8-bis(phosphono)tricyclo[5.1.0.02-~]oct-5-enes (9a-e). A temperature-dependent valence-isomeric equilibrium 7 & 8 is proved for 7 a by n. m. r. spectroscopy. p-Xylene reacts with photolytically generated (dimethy1phosphono)-phenylcarbene exclusively with formation of H-abstraction products (16, 17, 18), whereas p-dichloro-and p-dimethoxybenzene react with (phosphono)arylcarbenes to yield the 2.5-dichloro-and 2.5-dimethoxynorcaradienes 19a-d. These as well as the norcaradienes 21 a, b, and 23, formed from carbenes and o-disubstituted benzenes, possess a n unusual thermal stability. The phosphono group apparently takes the exo-position in all cyclopropane compounds, as can be deduced from the 15-17 Hz coupling of 3IP with cis-P-hydrogen in the cyclopropane 32. Some norcaradienes were characterized by Diels-Alder adducts (34a -h). Phosphono-ar yl-diazomethaneFur die Herstellung von Phosphono-aryl-diazornethanen eignet sich die BamfordStevens-Reaktion, wie bereits fruher fur 4 b gezeigt wurde 8) ; nach der gleichen Methode wurden auch die Diazoverbindungen 4a, c und d erhalten: die Kondensation der durch Michaelis-Arbusov-Reaktion zuganglichen Aroylphosphonsaure-dialkylester 1 a, c und d mit p-Toluolsulfonsaurehydrazid liefert zunachst Gemische der synlanfiisomeren p-Tosylhydrazone 3 bzw. Za, c und d; durch fraktionierte Kristallisation wurden bis auf 3d alle geometrischen Isomeren rein erhalten. 76H4-X-(P)RO\ /c, Cyclopropanierung pdisubstituierter BenzoleVon der Umsetzung p-disubstituierter Benzole mit Phosphono-aryl-carbenen erhofften wir uns neben einer Vereinfachung der Norcaradien-NMR-Spektren vor allem weitere Auskunfte iiber die das Norcaradien-System stabilisierenden Faktoren. Wenig ermutigend verliefen zunachst photolytische Cyclopropanierungsversuche von pXylol mit Dimethylphosphono-phenyl-carben ( Cyclopropanierung o-disubstituierter BenzoleDie Bestrahlung von Dimethylphosphono-phenyl-diazomethan (4a) in o-Dichlorbenzol hebt sich insofern von der entsprechenden Umsetzung des p-Isomeren ab, als das unsymmetrische 2.3-Dichlor-7-dimethylphosphono-7-phenyl-norcaradien (21 a) gebildet wird und noch zusatzlich d...

The structure of PO-substituted norcaradienes. I. The crystal and molecular structure of 7-dimethoxyphosphoryl-7-phenylnorcaradiene

“…A similar case has been found for spiro (indene-l,7'-norcaradiene), where the norcaradiene structure is also stable in the crystal (Dreissig, Luger, Rewicki & Tuchscherer, 1973). The configuration of the molecule is that predicted from its n.m.r, spectrum (Scherer et al, 1972): the phenyl ring lies endo to the cyclohexadiene skeleton. The most surprising feature of the structure is that all bonds of the cyclopropane ring are equal within their standard deviations" C(1)-C(6) 1.5_35 (5) A, C(1)-C(7) 1.533 (4) A, C(6)-C(7) 1.526 (4) A.…”

The structure of PO-substituted norcaradienes. II. The crystal and molecular structures of dimethyl 2,5-dichloro-7-phenylnorcaradiene-7-phosphonate and dimethyl 2,5-dibromo-7-phenylnorcaradiene-7-phosphonate

“…This had been expected from the magnitude of the coupling constant 3jp., in the 1H n.m.r, spectrum (Scherer et al, 1972). The aromatic only arise from the exo phosphoryl group.…”

Preparation of α-ketophosphonates by a [3,3]-sigmatropoic shift of enolphosphonates

“…a-Ketophosphonates undergo a diverse range of reactions and therefore, have found many useful synthetic applications both towards the preparation of other organophosphorus compounds as well as the synthesis of non-phosphorus containing molecules [1]. For instance, the reduction of a-ketophosphonates affords the corresponding a-hydroxyphosphonates [2]; treatment of a-ketophosphonates with a Wittig reagent affords the corresponding vinylphosphonates [3]; the corresponding oximes [4] and hydrazones [5] can be obtained from the reactions of a-ketophosphonates with hydroxylamine and hydrazine; b,c-unsaturated-a-ketophosphonates can be epoxidized [6] and also undergo a very facile Diels-Alder cycloaddition both as diene [7] and hetero-dienophile [8]. Finally, C-P bond in aketophosphonates is susceptible to facile cleavage under nucleophilic attack, for instance during acidic and basic hydrolysis [9] and therefore, a-ketophosphonates can be considered as synthetic equivalents to acid chlorides.…”