Propargylic phosphorus compounds

For propargyl phosphorus compounds, examples with cyclotriphosphazenes 135 [342] (Scheme 1.60), phosphinates 137 [343] (Scheme 1.61) and phosphonates 139 [344] (Scheme 1.62) have been published. 

Previous syntheses of terminal alkynes from aldehydes employed Wittig methodology with phosphonium ylides and phosphonates. 6 7 The DuPont procedure circumvents the use of phosphorus compounds by using lithiated dichloromethane as the source of the terminal carbon. The intermediate lithioalkyne 4 can be quenched with water to provide the terminal alkyne or with various electrophiles, as in the present case, to yield propargylic alcohols, alkynylsilanes, or internal alkynes. Enantioenriched terminal alkynylcarbinols can also be prepared from allylic alcohols by Sharpless epoxidation and subsequent basic elimination of the derived chloro- or bromomethyl epoxide (eq 5). A related method entails Sharpless asymmetric dihydroxylation of an allylic chloride and base treatment of the acetonide derivative.8 In these approaches the product and starting material contain the same number of carbons. 

The reaction is stereoselective with respect to the allene moiety when nonracemic propargylic carbonates are used as starting materials. This feature was employed in the synthesis of dinucleotide allenylphosphonothioate analog 197 containing both a stereogenic phosphorus center and allene moiety (Scheme 47.50). Compounds with diverse structural features at the phosphoms center and in the allene part can be obtained by this method. ... 

Kalek M, Johansson T, Jezowska M, Stawinski J. Palladium-catalyzed propargylic substitution with phosphorus nucleo-philes efficient, stereoselective synthesis of allenylphospho-nates and related compounds. Org. Lett. 2010 12 4702-4704. 

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