Allenic phosphines

The reaction of monoacylhydrazide with 1,2-allenic phosphine oxide 148 afforded /f iminylphosphine oxide 150. Here the unreacted C=C bond in the aUylic phosphine oxide 149 tautomerized to form a C=N bond during the reaction (Scheme 10.72) [77]. 

The intermediate product 162, formed from the nudeophilic addition of 1,2-alle-nic phosphonate or 1,2-allenic phosphine oxide with allylic alcohol, would also undergo a Claisen rearrangement to form 2-oxo-5-alkenyl phosphonate or phosphine oxide 163 [85], The rearrangement is accelerated by the carbanionic nature of the intermediate 162. For the conjugate addition step, the reaction temperature is crucial since the reaction at 0 °C afforded mainly /i,y-unsaturated product whereas a,/8-unsaturated products were formed at 20 °C. 

Likewise, a systematic use of such anisotropy effects has been used to establish the conformation of small rings from the proton shielding in the corresponding allenic phosphine oxides,<1967,153tol56 1968,46 1969 164 to 166) for example in 170. 

Me3Si)2NP=ESiMe3 (1 E = CH 2 E = N) with a diverse series of unsaturated organic substrates are reported. For example, phosphines 1 and 2 react readily with allenes via an ene process to afford novel phosphorus-substituted dienes or with 2-butyne to give allenic phosphines. Other derivative chemistry, including the addition of terminal acetylenes and acetylenic alcohols to the P=E bond as well as some related reactions with acetylenic halides and both P- and y-diketones, is also described. 

Since dialkyl acetylenes contain two sp hybridized carbon centers, they have the potential, like allenes, to undergo ene reactions. This prompted us to investigate the reaction of 2-butyne with the two-coordinate phosphines (eq 3). Initially, we found that this reaction was extremely slow at room temperature. Due to the high volatility of 2-butyne, we then carried out the reactions in sealed glass ampoules at 80 °C without solvent. In this case, the reactions were completed after 10 - 15 days and the novel allenic phosphines (5) were isolated in good yields. The simplicity of this reaction makes it a very useful method for the synthesis of here-to-fore unknown allenic phosphines. 

Similarly, heating the phosphinimine with 1-hexyne in benzene afforded the analogous allenic phosphine (6a eq 4). It is interesting to note that we observed two diastereomers for this product in the NMR spectra ( H, and 31p) as a result of the chirality of the allenic moiety in this case. When the same reaction of the phosphinimine with 1-hexyne was carried out at room temperature without a solvent, however, a surprisingly different course was observ (eq 4). Thus, instead of the expected ene reaction, we found that the C-H bond of the acetylene underwent addition to the P=N double bond to yield an acetylenic phosphine (6b). 

Several allenic phosphinic esters of the type 217 have been prepared from the appropriate acetylenic alcohol, HOCR 2C=CR, and a phosphonous dichloride,, or... 

The phenolic phosphines (58) are easily accessible by acid-cleavage of the related methyl ethers. The reactions of the enyne-phosphines (60) with Grignard or alkylsilver reagents lead to the allenic phosphines (61). The thienylphosphines (62) are formed in the reactions of thiophenes with halogenophosphines in the presence of zinc. ... 

A series of N-propargylaminophosphines (15)—(19) has been prepared in order to study their propensity to rearrange (15)—(17) were thermally stable, but (18) and (19) rearranged spontaneously to the A-methyl-3-phosphinopro-penal imines (20) and (21), respectively. This contrasts with the behaviour of the analogous propargyloxy compounds (22) which give allenic phosphine oxides. ... 

Four-bond phosphorus-proton couplings V(PH) in allenes are reported in Ref. 163 for allenic phosphineoxides (phosphonylallenes) 256-259, 32 and allenic phosphines (phosphinylallenes) 260-263,130. 

Allene complexes and coordination compounds that readily bind allenes often catalyze oligomerization and polymerization of allenes. Allene, phosphine, phosphine-carbonyl, phosphite, olefin, carbonyl, etc. complexes of metals of groups 8-10 exemplify such behavior, for instance, [Ni P(OR)3 4], [Ni(PR3)4], [Ni(CO)2 (PR3)2], [Ni(COD)2], [Rh2Cl2(CO)4], [RhCl(PPh3)3], [Rh(acac)(CH2 = C = CH2)2], etc. 

An efficient procedure for the synthesis of 2-pyrazolines from unsaturated hydrazone derivatives obtained from allenic phosphine oxides and acethy-drazide or benzhydrazide was described. ... 

J. Berlan and K. Koosha, J. Organometallic Chem., 1978,152,359 ibid., 153,99,109. Me2CuLi and allenic phosphine oxides, carbonyls, sulphones, sulphoxides. 

Methoxyallene has previously been used to prepare acetylenes via its reaction with Grignard reagents, in the presence of copper(i) halides.The use of preformed dialkylcuprates, however, gave the vinyl ethers instead. The E Z ratio varied with the substituent but it is difficult to explain why the difference is observed.Methoxyallene has also been converted into its vinyl anion and used in the synthesis of dihydrofurans and furans in an analogous way to ordinary vinyl ethers.Similarly allenic cuprates have been prepared and used in the synthesis of allenes and allenic pheromonessome examples are outlined in Scheme 58. The addition of lithium dimethylcuprate to allene phosphine oxides and allenic ketones was interpreted in terms of a 1,2- rather than a 1,4-addition process, in contrast to a/3-unsaturated... 

---