16650-30-9Relevant articles and documents
Ruthenium Catalyzed Diastereo- and Enantioselective Coupling of Propargyl Ethers with Alcohols: Siloxy-Crotylation via Hydride Shift Enabled Conversion of Alkynes to π-Allyls
Liang, Tao,Zhang, Wandi,Chen, Te-Yu,Nguyen, Khoa D.,Krische, Michael J.
supporting information, p. 13066 - 13071 (2015/10/28)
The first enantioselective carbonyl crotylations through direct use of alkynes as chiral allylmetal equivalents are described. Chiral ruthenium(II) complexes modified by Josiphos (SL-J009-1) catalyze the C-C coupling of TIPS-protected propargyl ether 1a with primary alcohols 2a-2o to form products of carbonyl siloxy-crotylation 3a-3o, which upon silyl deprotection-reduction deliver 1,4-diols 5a-5o with excellent control of regio-, anti-diastereo-, and enantioselectivity. Structurally related propargyl ethers 1b and 1c bearing ethyl- and phenyl-substituents engage in diastereo- and enantioselective coupling, as illustrated in the formation of adducts 5p and 5q, respectively. Selective mono-tosylation of diols 5a, 5c, 5e, 5f, 5k, and 5m is accompanied by spontaneous cyclization to deliver the trans-2,3-disubstituted furans 6a, 6c, 6e, 6f, 6k, and 6m, respectively. Primary alcohols 2a, 2l, and 2p were converted to the siloxy-crotylation products 3a, 3l, and 3p, which upon silyl deprotection-lactol oxidation were transformed to the trans-4,5-disubstituted γ-butyrolactones 7a, 7l, and 7p. The formation of 7p represents a total synthesis of (+)-trans-whisky lactone. Unlike closely related ruthenium catalyzed alkyne-alcohol C-C couplings, deuterium labeling studies provide clear evidence of a novel 1,2-hydride shift mechanism that converts metal-bound alkynes to π-allyls in the absence of intervening allenes.
SYNTHESE DE COMPOSES DIHYDRO-2,3 FURANNIQUES PAR HYDROBORATION D'ALCOOLS β-ACETYLENIQUES
Dana, Gilbert,Figadere, Bruno,Touboul, Estera
, p. 5683 - 5684 (2007/10/02)
Hydroboration of β acetylenic alcohols followed by NaOH/H2O2 oxidation leads to hemiacetals of γ aldols which are easily dehydrated to 2,3-dihydrofuran compounds.The reaction gives good yields with hindered alcohols and its stereochemistry may be controlled during the organometallic synthesis of the starting alcohol.
