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1.2- Oxaphospholanes reactions with

Secondary phosphines with a /3-hydroxyethyl substituent, obtained by addition of primary phosphines to a-oxides, easily undergo a reaction with ketones and aldehydes, giving 1,3-oxaphospholanes (6) [Eq. (4)] (72T2587). [Pg.62]

The reaction of diacetone alcohol 1 with alkyldichlorophosphines afforded 3-chloro-l,2-oxaphospholane-2-oxide 2. The latter undergo isomerization followed by dehydrochlorination to the corresponding 1,2-oxaphosphole derivatives 3 (Scheme 1) [29],... [Pg.36]

The reaction of oxaphospholanes 235 derived from 3-hydroxy-3-arylphosphonium salts 234 and DBU with paraformaldehyde yielded 4-aryl-6-methylene-l,3-dioxepanes 89 (Scheme 69) <2005BCJ2209>. [Pg.357]

In the second reaction type, the ene and yne functionalities are found in two different phosphorus substituents. These 1-alkynylphosphonates undergo facile Pd(OAc)2-LiCl-catalyzed cyclization to give oxaphospholanes in good yields (77-89%, Scheme 1.27) but with low stereoselectivity, ratios at the exo double bonds being approximately 60/40. ... [Pg.32]

Oxo-l,2-azaphospholanes 122 were also obtained from the reaction of 1,2-oxaphospholanes 62 and anilines proceeding via the formation of linear (3-anilinopropyl)methylphosphinic acids (Scheme 76) [140] followed by cycliza-tion with elimination of water. [Pg.145]

Oxaphospholans.—Full details have appeared of the reactions of the lactone and dione dimers of dimethylketen with a series of tervalent phosphorus esters and amides, and the postulated quinquecovalent intermediate (49) from the lactone dimer has been isolated in one case. Of potential mechanistic significance is the preferred migration of exocyclic substituents in the steps corresponding to (49) (50). [Pg.41]

The interaction of a dialkyl hydrogenphosphonate with a 3-hydroxyalkanal to afford mixtures of diastereoisomers of the linear dialkyl (l,3-dihydroxyalkyl)phosphonate and derived 1,2-oxaphospholane 2-oxides has already been discussed. Lack of protection at appropriately sited hydroxy groups in carbohydrate molecules allows a similar reaction to occur. With D-erythrose, the 1 1 adduct is obtained as a mixture of epimers 324 (R, R = H, or OH) on acid-catalysed cyclization, these yield the phosphorus epimeric analogues of D-ribo and D-arabino-furanosides with phosphorus in the epimeric position 324 (R = H, R = OH) affords 325 as a mixture of the 2R, 35,4R, 5R and 25, 35,4R, 5R, forms in the ratio 2 1, and 324 (R = OH, R = H) also yields the phosphorus epimeric 321 in the same ratio ... [Pg.208]

Very few reports have been concerned with phosphorus chlorides of the types (RO)2PCl or ROPCI2. For the former (R = Et), the product from propenoic acid consists of the linear ester 465 (R = OR, R = Et R = R" = although readily transformed, when heated comparatively gently, into the corresponding 2-ethoxy-2-oxo-l,2-oxaphospholan-5-one (466), and that from 2-methylpropenoic acid consisted of the corresponding 4-methyl derivative 466 (R" = However, a detailed study of the reaction between (EtO)2PCl... [Pg.236]

Some reactions have been carried out with the ester chlorides 462 (R = alkyf and aryf" ) when the phosphinic acid derivatives 465 were isolated in essentially pure form, but these also, when distilled, afford 1,2-oxaphospholanes 466 " " ... [Pg.236]

Oxophospholanes 199 were obtained by cyclization of hydroxyl-containing a-fluorineohisohinic acids.Oxaphospholanes 200 were prepared by the reaction of 4,4,4-trifluoro-3-hydroxy-l-phenylbutane-l-one with dichlorophosphines, and oxaphospholanes 202 by the ring closure reaction of phosphonates 201. " ... [Pg.202]

Mono- or difluorophosphonates la and lb were reacted with trimethyl-silyl bromide leading to the phosphonic adds 2a and 2b after solvolysis in methanol (Scheme 1). 5-Substituted 1,2-oxaphospholane formation was accomphshed by intramolecular DCC-mediated couphng. The last step consisted of the formation of the esters 3a and 3b by reaction of the appropriate fatty acyl chloride in the presence of pyridine. [Pg.133]


See other pages where 1.2- Oxaphospholanes reactions with is mentioned: [Pg.140]    [Pg.265]    [Pg.197]    [Pg.113]    [Pg.320]    [Pg.329]    [Pg.179]    [Pg.309]    [Pg.212]    [Pg.347]    [Pg.457]    [Pg.195]    [Pg.156]    [Pg.193]    [Pg.617]    [Pg.135]    [Pg.457]   
See also in sourсe #XX -- [ Pg.4 , Pg.10 , Pg.411 ]




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Oxaphospholans

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