P-Alkynylation

In line with the known similarity between the chemistry of Si and P, alkynyl phosphorus species undergo a similar rearrangement (Eq. 2.79) [58]. 

Dolphin has employed the Sonogashira coupling of terminal alkynes with zinc(II)-10-iodo-5,15-diphenylporphyrin (126) to prepare a series of alkynyl derivatives 127 [87], and similar syntheses of p-alkynyl porphyrins have been described [88]. 

The aza-Bergman rearrangement of C,A-dialkynylimines to p-alkynyl acrylonitriles has also been studied intensively. In 1997, David and Kerwin investigated the thermochemistry of (Z)-118 in solution and observed rearrangement to (Z)-119... 

Isomerization of p-Alkynyl Allylic Alcohols to Furans Catalyzed by Silver Nitrate on Silica Gel 2-Pentyl-3-Methyl-5-heptylfuran. 

The reaction of the P-alkynyl silylated phosphoranimine (71) with KP(H)Ph yields a cyclic product which adopts a polymeric structure (72) after careful recrystallization from diethyl ether. The formation of the cyclic structure probably arises from addition of [P(H)Ph] to the phosphoranimine, followed by a 1,3-H shift from phosphorus to carbon. In the structure of (72) each potassium atom is coordinated to one N atom and two P(III) atoms from different ligands with a mean K-P distance equal to 327.3(6) pm. Attack at the carbon atom adjacent to P(V) has been observed for the reaction of (73) with LiP(R)Ph (R = H or SiMe3Bu ), affording the products (74a) and (74b). The tin analogues (75a) and (75b) can be prepared in low yield by the reaction of SnCb with (74a) and (74b), respectively. ... 

ISOMERIZATION OF p-ALKYNYL ALLYLIC ALCOHOLS TO FURANS CATALYZED BY SILVER NITRATE ON SILICA GEL, 76, 263... 

To complete the range of geometric isomers of terminal and non-terminal dienes and trienes available, systems nominally derived from inaccessible (Z)-alkenylzirconocenes are desirable. Fortunately, insertion of the various carbenoids discussed above into mono- or bis(alkynyl) zirconocenes 64 and 65 affords dienyne products 66 [38], which are readily reduced to the desired (E,Z,Z)-trienes (Scheme 3.15) [45—47]. Insertion of the P-alkynyl carbenoid 62 allows a convenient access to (Z)-enediynes 67. 

Stereoselective reaction of P-alkynyl-P-lactones gives rise to 3,4-alkadienoic acids. A product of this type has been recognized as a suitable precursor of malyngolide. ... 

Matsuda and co-workers found that silyl enol ethers of thiol esters are good nucleophiles in the reaction with propargylic-type esters to form p-alkynyl thiol esters in the presence of a catalytic amount of [Ir(cod)(POPh3)2]OTf 32 [37]. The acetoxy group of 29 was readily substituted at 25 °C to form thiol ester 31 with 93% yield by simply stirring together 29,4 equiv of silyl enol ether 30, and 32 (5 mol%) (Eq. 16). 

ASYMMETRIC REDUCTION OF PROCHIRAL a, P-ALKYNYL KETONES TABLE 21.1 a-Pinene-9-BBN Complex... 

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