1,3,2-Dioxaphospholane

Conformation problems in five- and six-membered rings containing phosphorus continue to attract attention and, using n.m.r., i.r., and dipole-moment measurements, studies have been reported on 1,3,2-dioxaphospholan systems (118), > 1,3,2-dioxaphosphorinane systems... 

The reactions of 1,3,2-dioxaphospholans (23)-(26) with five acceptor alkenes (27)—(31), and of trimethyl phosphite, tris(dime-... 

The mechanism of the reaction involves oxaphosphole ring closure followed by 1,3,2-dioxaphospholane rind opening. 

Dioxaphospholans.—1,2-Diols with TDAP and carbon tetrachloride gave either epoxides (46) or, more commonly, spirophosphoranes (47).37 cw-Cyclohexane-... 

A synthesis of alkenes from 1,2-diols depends upon the initial formation of the 1,3,2-dioxaphospholans (128), followed by rupture of the heterocyclic ring and removal of phosphorus with Li-NH3 or Na-Ci 0H 8. The reaction is reasonably stereo-... 

Alkenes are much less reactive in the H-P bond addition reactions than alkynes. However, 1,3,2-dioxaphospholane 2-oxide (4a), a five-membered hydrogen phosphonate of pinacol, is exceptionally reactive with alkenes although dialkyl and diaryl phosphonates such as 4b-d are totally unreactive (Scheme 25) [26]. Very interestingly, six-membered hydrogen phosphonates 4e,f are also unreactive under identical conditions. 

The two-step deoxygenation of benzoyl cyanide to phenylcyanocarbene, which added quickly to alkenes via photolysis of the appropriate 2,2-dihydro-1,3,2,-dioxaphos-pholanes, has been performed70. A homolytic fragmentation mechanism was assumed. When the 1,3,2-dioxaphospholane 36 in trans-butene was irradiated, the range of observed substances included 37 and 38 as the major products, in addition to fluorenone and bifluorenylidene (equation 16)70. 

Spiro[ 1,3,2-dioxaphospholane-2,1 -[2,6,7]-trioxa[ 1 ]phos-phabicyclo[2.2.2]octane]... 

Published data on the reaction of isatin with di- and trialkyl phosphites are somewhat contradictory. In particular, the authors in [78] showed that isatin with trialkyl phosphite forms 2 1 adduct, which has the structure of 1,3,2-dioxaphospholane containing a pentacoordinated phosphorus atom. More recently analogous results were obtained in the reaction of isatin with amidophosphites [79], At the same time it was shown [80] that 5-methylisatin reacts with trialkyl phosphites with the formation of 3-dialkoxyphosphoryl-3-hydroxy-2-indolinones, identical with the compounds obtained in the reaction of isatin with dialkyl phosphites [78]. In the monograph [4] with reference to the patent [61] the reaction of diethyl phosphite with isatin under the conditions of the Abramov reaction was indicated to lead to 3-dialkoxyphosphoryl-2-indolinone. In all probability this needs verification. 

These published data prompted the authors [82] to undertake a more detailed study of the phosphorylation of isatin by the esters of P(III) acids and hydrophosphoryl compounds. At room temperature in the absence of traces of moisture isatin 49a, 1-acetylisatin 49b, and 5-bromoisatin 49c react with trialkyl phosphites and phosphonites with the formation of the unstable 1,3,2-dioxaphospholanes 87 with a pentacoordinated phosphorus atom, which isomerize in alcohol solution to the stable phosphoryl compounds 88 ... 

Chlor-1,3,2-dioxaphospholane erleiden im Gegensatz zu 2-Chlor-l,3,2-benzodioxa-phosphol bei der Reaktion mit Acetalen Ringoffnung354 ... 

Phosphonsaure-anhydride reagieren in Chloroform im geschlossenen Rohr mit Oxiranen innerhalb 3—6 Stdn. bei 80-100° zu 2-Alkyl(bzw. Aryl)-1,3,2-dioxaphospholan-2-oxiden467 ... 

Substituierte Ethen-468 und Alkoxymethan-phosphonsaure-anhydride469 konnen nach der gleichen Methode in die entsprechenden 1,3,2-Dioxaphospholane iibergefiihrt werden. 

Dimethyl-2-hydroxy-1,3,2-dioxaphospholan-2-sulfid-Iiiiidazoliuni-Salz 5 Zu ciner L6sung von 2,72 g (0,02 mol) 4,5-Dimethyl-1,3,2-dioxaphospholan-2-oxid und 1,36 g (0,02 mol) Imidazol in Benzol gibt man 0,64 g (0,02 mol) Schwefel. Nach 2 Stdn. wird das auskristallisierte Salz abgesaugt und aus Propanol/Ethylether umkristallisiert. Ausbeute 2g(85%) Schmp. 117-118°. 

Mit Glykol bzw. Brenzcatechin erhalt man in nahezu quantitativen Ausbeuten 2-Mercap-to-1,3,2-dioxaphospholan- bzw. - l,3,2-benzodioxaphosphol-2 -sulfid247. 

Trialkyl-1,3, 225-oxazaphospholane ergeben beim Erhitzen Phosphanoxide und Aziridine7v bzw. 2,2,2-Triaryl-1,3,2-dioxaphospholane Phosphanoxide und Oxirane80 ... 

Dimethyl-2-hydroxy- -sulfid-Imidazolium-Salz aus 4,5-Dimethyl-1,3,2-dioxaphospholan-2-oxid und Imidazol E2, 663... 

For the sensitive and selective detection of trace amounts of low-molecular-weight alcohols and other hydroxyl-containing compounds by means of the alkali FID, Vilceanu and Schulz [43] prepared phosphorus-containing derivatives. Derivatives 5.1 and 5.2 were prepared by the reaction with 2-chloro-l, 3,2-dioxaphosphorinane (5.3) and 2-chloro-1,3,2-dioxaphospholane (5.4), respectively, in the presence of triethylamine in benzene, which proceeds very quickly, and were particularly suitable for the determination of trace amounts of alcohols in non-alcoholic and anhydrous media. Retention indices of these derivatives of alcohols up to C5 are listed in Table 5.4. 

A third type of five-membered cyclic oxyphosphorane is represented by derivatives of the 1,3,2-dioxaphospholene -10,12,18 and the 1,3,2-dioxaphospholane ring systems. These compounds are made from the reactions of trivalent phosphorus compounds and certain mono- and dicarbonyl functions, (73).J5 Some a-diearbonyl structures furnish... 

The n.m.r. spectrum of the cis-1,3,2-dioxaphospholane (90) in Scheme 16 shows one signal each for the CH30-, CHsCO-, and CH3-C-groups, at + 30°, which corresponds to positional exchange of ligands according to the itinerary of Fig. 18-III. 

The reaction of the aminophosphanes t-Bu2PNH2 and F2PNH2 results in the formation of hexafluoroacetoneimine and phosphoric acid derivatives with and without addition of HFA. With aminodifluorophosphane, the expected formation of a 1,3,2-dioxaphospholane (see Section III,A,4) has been observed (263). 

The reaction of HFA with tris(dimethylamino)phosphane leads mainly to the formation of tris(dimethylamino)difluorophosphorane and a smaller amount of hexamethylphosphoric acid triamide, although indirect evidence for the formation of 1,3,2-dioxaphospholanes (Section III,A,4) has been found (277). 

The reaction of monoammonium perfluoropinacolate with 2-amino-1,3,2-dioxaphospholane (52) provides a spirocyclic phosphorane 53 with hydrogen attached to phosphorus, with evolution of ammonia occurring 263). 

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