Highly efficient synthesis of propargyl- and allenyltitanium reagents from propargyl halides or propargyl alcohol derivatives. Practical synthesis of allenyl and homopropargyl alcohols

Regioselective Addition of Tris(dialkylamino) Phosphines to [Fe2(CO)6(μ-PPh2){μ-η1:η2-(H)CCCH2}]: Novel P−C Coupling Reactions and Unusual Hydrocarbyl Rearrangements

“…6 In addition, the fundamental reactivity of mononuclear η 3 -and binuclear σ-η 2 -coordinated propargyl and allenyl ligands has attracted considerable academic interest, and numerous examples of unusual reactivity patterns have been reported. 1 While the reactivity of mononuclear cationic transition metal allenyl complexes has been well documented, dominated largely by the generation of central carbon-substituted allyl derivatives via regiospecific addition of nucleophiles to the central carbon atom, 7 the reaction chemistry of binuclear allenyl complexes is far more diverse.…”

“…13 In the case of neutral phosphorus-based nucleophiles various reaction pathways are possible, the two most common of which are carbonyl substitution and addition to the coordinated hydrocarbon. 14 In this regard, we have recently begun to investigate the reactivity of the diiron allenyl complex [Fe 2 (CO) 6 (µ-PPh 2 ){µ-η 1 :η 2 -(H)C R d C dC γ H 2 }] (1) and discovered an unprecedented nucleophilic attack of diphenylphosphine at C R to afford the phosphino-substituted µ-η 1 :η 2 -alkenyl complex 6 (µ-PPh 2 ){µ-η 1 :η 2 -CH 3 CdCH(PPh 2 )}]. 8b Mono-and bidentate tertiary phosphines also undergo regiospecific P-C R bond formation with 1.…”

2.05 Propargyl and Allenyl Organometallics

“…Introduction of a terminal silyl substituent into the propargyl halide inverts regioselectivity; g-functionalized propargyl halides furnished allenyl alcohols with excellent stereocontrol (84-97% ee) under the catalysis of complex 135. 53 In addition to silyl substituents, simple alkyl and aryl counterparts could be successfully employed (Scheme 30, 55 Terminally unsubstituted propargyl compounds allowed good yields of homopropargyl alcohols; functionalization of the alkyne terminus reverted regioselectivity toward allenyl alcohols. Secondary and tertiary propargyl alcohols derivatives favored propargylation, which proceeded with good yields and moderate diastereoselectivity.…”

Intramolecular cyanoboration of alkynes via activation of boron–cyanide bonds by transition metal catalysts

“…Methyl vinyl ketone (Wako) was obtained from the commercial source and purified by distillation. Pd(PPh 3 ) 4 [16], Pd 2 (dba) 3 -benzene [17], PdCl 2 (MeCN) 2 [18], bis(diisopropylamino)cyanoborane [8], and 4-methyl-1-heptyn-4-ol [19] were prepared according to the literature methods.…”