Studies on highly regio- and stereoselective selenohydroxylation reaction of 1,2-allenyl phosphine oxides with PhSeCl

Highly Selective Synthesis of [(Z)‐3‐Chloro‐2‐(phenylselanyl)‐1‐alkenyl]phosphonates and 2‐Ethoxy‐4‐(phenylselanyl)‐2,5‐dihydro‐1,2‐oxaphosphole 2‐Oxides by Electrophilic Reaction of 1,2‐Alkadienylphosphonates with PhSeCl

“…It is interesting to observe that the stereoselectivity is different from that of the iodo-and selenohydroxylation reactions of (1,2-alkadienyl)diphenylphosphane oxides. [1,2] In our previous studies of the halohydroxylation reaction we also observed (Z) stereoselectivity, which was rationalized in terms of a steric effect [13] or a soft Lewis acid/base interaction. [14] It is proposed that the reaction proceeds through an equilibrium between the three-membered selenonium intermediates (E)-4 and (Z)-5.…”

“…Then a solution of 1a (70.6 mg, 0.3 mmol) in MeCN (1.5 mL) was subsequently added, and the resulting mixture was stirred at room temp. for 2 h. The mixture was worked up with H 2 O (5 mL) and extracted with diethyl ether (3 ϫ 20 mL), washed with brine (5 mL), and dried with anhydrous Na 2 …”

“…Recently, we observed that in the halo-and selenohydroxylation reactions of allenylphosphane oxides, [1][2][3] the electrophilic moiety was added to the central carbon atom of the allene moiety with the hydroxy group always attached to the 3-position with respect to the phosphorus atom; the excellent regio-and (E) stereoselectivity of the reactions has been rationalized in terms of the neighbouring-group participation ability of phosphane oxide. [1,2] However, when 1,2-alkadienylphosphonates were used, the chemistry was different: Angelov and co-workers reported that the reactions of allenylphosphonates with RSeCl led to (E)/(Z) mixtures of [2-(alkyl-or phenylseleno)-3-chloro-1-alkenyl]-phosphonates.…”

“…[1,2] However, when 1,2-alkadienylphosphonates were used, the chemistry was different: Angelov and co-workers reported that the reactions of allenylphosphonates with RSeCl led to (E)/(Z) mixtures of [2-(alkyl-or phenylseleno)-3-chloro-1-alkenyl]-phosphonates. [4] Macomber et al reported that dimethyl (propa-1,2-dienyl)phosphonate reacted with 1.0 equiv.…”

Bifunctionalized Allenes, Part XI: Competitive Electrophilic Cyclization and Addition Reactions of 4‐Phosphorylated Allenecarboxylates

“…Thus, the reaction of electrophilic reagents with dialkyl allenephosphonates or allenyl phosphine oxides leads to 2,5‐dihydro‐1,2‐oxaphospholes or/and 2,1‐ or/and 2,3‐adducts or a mixture of them, depending on the degree of substitution at the C1 and C3 atoms of the allenic system, the nature of these substituents, and the type of the reagents. Recently, it was also observed by Ma and co‐workers that the electrophilic iodohydroxylation , fluorohydroxylation , and selenohydroxylation reactions of allenyl phosphine oxides with iodine, Selectfluor, and benzeneselanyl chloride, affording 2‐iodo(respectively, 2‐fluoro or 2‐phenylselanyl)‐3‐hydroxy‐1( E )‐alkenyl phosphine oxides with high regio‐ and stereoselectivities, which the authors believed to be determined by the neighboring group participation effect of the diphenyl phosphine oxide functionality. More recently, we have reported the reactions of 1‐vinyl‐ [15a] and 3‐vinylallenyl [15b] phosphine oxides with electrophiles leading to formation of various heterocyclic or highly unsaturated compounds.…”