Phosphoranes cyclic

The reaction of cyclic trans-1,2-diols with DEAD and TPP generally gives the corresponding oxiranes via phosphoranes. Cyclic cis-1,2-diols also react with DEAD/TPP to afford primarily phosphoranes (26) which decompose into final product(s) such as oxiranes (with retention of configuration) (eq 21) and dehydrated alcohols and/or ketones (eq 22). ... 

The formation of 27a-27e, 28, and 29 makes use of a chemistry developed by Akiba and coworkers in the 1990s for the synthesis and applications of cyclic lO-P-5 phosphoranes made of two Martin ligands. Methyl, benzyl and phenylth-... 

Finally, new tricyclic hexacoordinated phosphoranes with internal P-N coordination were synthesized by Swamy and coworkers by oxidative addition of cyclic phosphite precursors with quinones or with a combination of diols and (z-Pr)2NCl [57, 58]. Various ring sizes from five to eight membered were obtained showing the generality of the approach. A selection of compounds (47a-47e) is presented in Fig. 8. 

A number of preparations of mixed halogenophosphoranes from tervalent phosphorus-fluorine compounds have been reported. For example, acyclic and cyclic fluorine compounds have been converted to phosphoranes, such as (36) and (37), by treatment with chlorine. Similar reactions leading to AA-dialkylaminodichlorodifluorophosphoranes (38) have been described and the stability of (38) to exchange processes commented upon. iVA-Dialkylaminotetraiodophosphoranes (39) have been prepared from AA-dialkylaminodichlorophosphines and lithium iodide, although no detailed physical evidence for the structure of these unusual compounds has yet been reported. The preparation of bis-(A-alkylamino)difluorophosphoranes (4) has been described above (see Section lA). 

B. Electrophilic Reactions.—Transesterification followed by rearrangement is a common route from simple phosphites to more complex phos-phonates. This has now been applied to the preparation of cyclic phos-phonates (85). Both phosphites (86) and phosphoranes (87) containing phosphorus-hydrogen bonds are obtained from the cyclic biphosphite (88) and butanol. ... 

Reaction of perthiophosphonic anhydrides (64) with amines leads first to (105) and then, by further attack, to (106). With ammonia itself the second addition proceeds at the same phosphorus atom as the initial attack, giving (107) and (108). The anhydride (64) is also reported to react with 1,3-dioIs to give cyclic phosphonyl disulphides (109). Thermal decomposition of phenylphosphinic anhydride (110) may lead to the formation of PhP since in the presence of benzil the formation of the phosphorane (111) was observed. ... 

The pioneering work of Denney et ai19 on the synthetic utility of oxyphosphoranes has been thoroughly exploited by Evans et al. in demonstrating that diethoxytriphenylphosphorane promotes mild and efficient cyclodehydration of diols (e.g. 11) to cyclic ethers (e.g. 13) via the cyclic phosphorane (12)20>21. Simple 1,2-, 1,4-, and 1,5- diols afford good yields of the cyclic ethers but 1,3-propanediol and 1,6-hexandiol give mainly 3-ethoxy-l-pro-panol and 6-ethoxy-l-hexanol respectively whereas tri- and tetra-substituted 1,2-diols afford the relatively stable 1,3,2- diox-phospholanes. In some instances (e.g. 14), ketones (e.g. 16) are formed by a synchronous 1,2-hydride shift within (15). The synthetic utility has been extended to diethoxyphosphoranes supported on a polystyrene backbone22. 

The use of azodicarboxylates as a route to dioxaphosphoranes continues to attract attention. In the most recent contribution, triphenylphosphine and di-iso-propyl azodicarboxylate (43) are shown to react with prcpane-1,3-diol and butane-1,4-diol in THF at 0°C under high dilution conditions to give the expected six-and seven-membered-ring phosphoranes (44 ab)36. In more concentrated solution however, cyclic oligomers are formed. Substituted and ccnformationally restricted 1,3- and 1,4-diols form the expected cyclic phosphoranes without recourse to high dilution techniques. 

In a study of the reactions oi acyclic o-methoxyphenyl-phosphinites (45a), phosphonites (45b) and phosphites (45c) with halogens,the intermediate halogenophosphonium salts (46) are stabilised either by ligand exchange with starting material (not shown) or by elimination of methyl halides to form cyclic phosphoranes ( 47 ) 3 7. ... 

In the aprotic solvent acetonitrile, the trianion of cyclic trimetaphosphoric acid 115 is formed via the phosphorane 112 and the pyrophosphate dianion 113 protic solvents differ by reacting via the phosphorane 114 to give the phosphates 104 or H2PO . 

Structure 1 Generic representation of the structures of basic types of binary phosphorus-nitrogen heterocycles cyclophosphazanes (I), cyclophosphazenes (II), cyclic phosphoranes (III)... 

The cyclic phosphoranes so obtained demonstrate properties typical for the compounds with pentacoordinated phosphorus atom (Scheme 30) [78, 83],... 

Macomber et al. achieved formation of cyclic phosphoranes 82 [86], The latter on treatment with water or with alcohols gave the corresponding oxaphosphole derivatives (Scheme 34). 

Such phosphoranes are potential reducing agents mild oxidation of (4), or heating, gives the spirophosphorane (5) whereas (6) is slowly transformed into the spiro-phosphorane (7) at 0 °C.3 In general, cyclic PH-phosphoranes of structure (8) are in equilibrium in solution with the phosphorus(m) species (9).3... 

Oxaphospholans.—The stable phosphoranes (41) were obtained from ylides and epichlorohydrin.35 The formation of (41 R = H) from the action of base on the salt (42) supports a mechanism via the intermediate ylides (43). The crystalline cyclic... 

The phosphoranes, e.g. (69), which are intermediates in the Arbusov reactions of the cyclic phosphite (68) with chlorine, bromine, and benzenesulphenyl chloride have been detected at low temperatures by 31P n.m.r. spectroscopy.47 A similar technique revealed the intermediate (71) in the reaction of the thiophosphate (70) with chlorine.48... 

The deoxygenation of aryl 2-nitrophenyl sulphides with tervalent phosphorus compounds is analogous to that of the corresponding ethers except that in many cases the anticipated phosphoranes, e.g. (87), are thermally unstable.58 The extra stability of spirophosphoranes allows them to be isolated, e.g. (13), if cyclic phos-phonites are used in deoxygenation.8... 

Formate esters behave as typical carbonyl compounds in reactions with a number of ylides, eliminating phosphine oxide and forming vinyl ethers, e.g. (33).35 Stabilized phosphoranes are able to condense with the carbonyl group of cyclic thioanhydrides (34).38 Quinoline derivatives, e.g. (35), are obtained from the condensation of dicar-boalkoxy-ylides with isocyanates.37 Benzoyl isothiocyanates and keto-phosphoranes give quantitative yields of (36), which are unreactive in Wittig reactions but can be readily oxidized by selenous acid.38 The products obtained from reactions (Scheme 9) with the triazolinedione (37) depend upon the stability of the ylide used.39... 

Hydrogen-1. The Ha signal of the cyclic phosphonates (28) moved upheld to <5 6.2 p.p.m. when the N-aryl ring possessed two or/Ao-methyl groups.48 The shielding effect is even larger for the phosphorane (29), and Ha appeared at 5 5.9 p.p.m. 

A series of uridine 3 -alkylphosphates (308) undergo in alkaline solution a hydroxide-ion catalysed reaction to give the 2, 3 -cyclic monophosphates (309) via phosphorane-type intermediates (Scheme 35). The alkyl groups ranged from ethyl... 

However, dicarboxylic acid dichlorides treated with iminophosphoranes (Scheme 116) show a substrate-dependent reaction. Thus, o-benzodiacetyl dichlorides (321) form chloroazepinones (322) only with A -arylimino-phosphoranes. N-Alkyliminophosphoranes, upon elimination of dichloro-triphenylphosphorane and subsequent Mumm rearrangement (71M168), give the cyclic imide (323) (90S149 91T53). 

At low temperatures dioxetane adducts with trivalent phosphorus have been isolated by Bartlett and coworkers. These cyclic phosphoranes gradually decompose to give the corresponding epoxide and phosphine oxide (Scheme 39) (73JA6486). Aryl-substituted phosphines... 

At present, cyclic phosphoranes have been classified into four main families (Figure 4) monocyclic, bicyclic (spiro and fused), tricyclic and tetracyclic. 

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