54372-75-7Relevant academic research and scientific papers
One-pot synthesis of optically active allyl esters via lipase-vanadium combo catalysis
Akai, Shuji,Hanada, Ryosuke,Fujiwara, Noboru,Kita, Yasuyuki,Egi, Masahiro
supporting information; experimental part, p. 4900 - 4903 (2011/01/12)
The combination of vanadium-oxo compounds (3 or 4) with a lipase produced the regio- and enantioconvergent transformation of racemic allyl alcohols (1 or 2) into optically active allyl esters. In this system, the vanadium compounds catalyzed the continuous racemization of the alcohols along with the transposition of the hydroxyl group, while the lipase effected the chemo- and enantioselective esterification to achieve the dynamic kinetic resolution.
Trans-vinylboranes from 9-borabicyclo[3.3.1]nonane through dehydroborylation
Colberg, Juan C.,Rane, Anil,Vaquer, Jaime,Soderquist, John A.
, p. 6065 - 6071 (2007/10/02)
The hydroboration of 1-alkynes (1) was reinvestigated by 11B NMR under optimized conditions (THF, 18 h, 0°C) and found to provide trans-vinyl-9-BBN adducts (2) together with variable amounts of 1,1-diborylalkanes (3) depending both upon the excess of 1 employed and the nature of alkyne substitution. By contrast, the formation of 3 with 2 equiv of 9-BBN-H is quantitative. A new completely stereoselective route to 2 from 3 was discovered with its reaction with ArCHO in an electrocyclic process (p = 0.42). While analogous to the Midland reduction, the term dehydroborylation is introduced to emphasize the olefination aspect of the reaction. Compound 3a (R = Me) is smoothly dehydroborylated at 25°C with PhCHO following second-order kinetics. Competitive rate studies reveal its reaction to be slower than that of Alpineborane (7) (k7/k3a = 4.5) but faster than that of B-siamyl-9-BBN (6) (k6/k3a = 0.34). The value of the dehydroborylation approach to 2 and the advantages of using 9-BBN derivatives in vinylborane reactions are demonstrated with numerous examples. Thus, 1,8-nonadiyne is converted, through a bis(vinylborane) (11), to pure trans,trans-1,9-dideuterio-1,8-nonadiene (12). This transformation has not been previously possible for 9-BBN-H because of competitive dihydroboration. The dihydroboration of 1-(triethylsilyl)-1-propyne, after thermal isomerization and deuterolysis, affords trans-(3-deuterioallyl)silane (16), a most remarkable overall conversion. The insertion of aromatic aldehydes into 2 was further demonstrated to provide a convenient entry to trans-allylic alcohols. The selective oxidation of 2 with TMANO produces trans-alkenyl-9-oxa-10-borabicyclo[3.3.2]decanes, 18, which resist further reaction with ArCHO, oxidation in the atmosphere, and protonolysis. A 1→ 3 → 2 → 20 sequence was employed without the isolation of 2 in a one-pot Suzuki coupling with ArBr to provide trans-stilbenes (20, Ar = p-C6H4X, X = OMe (80%), NMe2 (60%)).
Diastereoselectivity in the [2,3]-sigmatropic rearrangement of substituted allylic N,N-dialkylamidosulfoxylates. X-ray molecular structure of [(1′) S*, (S)S*]-(2′E)-4-[[3′-(4″-bromophenyl)-1′-methyl- 2′-propenyl]sulfinyl]-morpholine
Baudin, Jean-Bernard,Bkouche-Waksman, Itka,Hareau, Georges,Julia, Sylvestre A.,Lorne, Robert,Pascard, Claudine
, p. 6655 - 6672 (2007/10/02)
By the reaction with three N,N-dialkylamidosulfenyl chlorides 2 bearing representative sizes for the R groups on the nitrogen atom, several substituted secondary E or Z allylic alcohols (1a-h) have been converted into the corresponding pairs of diastereoisomeric allylic sulfinamides (3+-3′a-v), whose ratios have been determined by 1H NMR spectroscopy. Five cases of entirely diastereoselective [2,3]-sigmatropic rearrangement have been observed. The stereochemistry of one pure diastereoisomer 3′m has been determined by single crystal X-Ray analysis. When treated with 4-morpholinesulfenyl chloride, cyclohex-2-en-1-ol is stereoselectively converted to one diastereoisomer of the sulfinamide 5b which, by unambiguous procedures, led to the sane p.tolylsulfoxide 5a already obtained by treatment of cyclohex-2-en-1-ol with toluene-p-sulfenyl chloride.
