Synthesis of enantioenriched homopropargylic alcohols through diastereoselective SE' additions of chiral allenylstannanes to aldehydes
摘要:
Allenylstannanes (S)-4 and (R)-4, available in ca. 90% ee from alkynones 1 through reduction with the LiAlH4-Darvon alcohol or -ent-Darvon alcohol complex, followed by S(N)2' displacement on the derived mesylates (R)-3 or (S)-3 with Bu3SnLi.CuBr.Me2S, readily add to various aldehydes under Lewis acid catalysis to afford optically active homopropargylic alcohols with good to excellent syn diastereoselectivity. With 2-(benzyloxy)propanal (48), MgBr2-catalyzed reactions are highly stereoselective, affording the syn adduct 49 from the (S)-stannane (S)-4 and the anti adduct 52 from the (R)-stannane (R)-4. BF3-promoted additions give mainly or exclusively the syn adducts 49 and 51. Additions of (S)- and (R)-4 to (R)-3-(benzyloxy)-2-methylpropanal (61) yield the syn adducts 62 and 64 as major or exclusive products.
Structure Investigations of (ent)-Cladospolide D by De Novo Synthesis and Kinetic and Thermodynamic Isomerization
作者:John Penn、George O’Doherty、Yalan Xing
DOI:10.1055/s-0029-1217606
日期:2009.9
dihydroxylation of a dienoate installed the remaining stereochemistry. The de novo asymmetric route allowed for the asymmetric synthesis of three members of the cladospolide natural products and correctly established the structure for cladospolide D. cladospolides B-D - asymmetric synthesis - natural product synthesis - E/Z-alkene isomerization
De Novo Asymmetric Synthesis of Cladospolide B−D: Structural Reassignment of Cladospolide D via the Synthesis of its Enantiomer
作者:Yalan Xing、George A. O’Doherty
DOI:10.1021/ol9000119
日期:2009.3.5
The enantioselectivesynthesis of cladospolide B, C, and (ent)-cladospolide D has been achieved in 11−15 steps from 1-nonyne. The route relies upon an alkyne zipper reaction to relay an ynone and dienoate functional groups across a nine carbon fragment, which enables a highly enantioselective Noyori ynone reduction and a diastereo- and regioselective Sharpless dihydroxylation of a dienoate. In addition
Stereospecific synthesis of trisubstituted and tetrasubstituted olefins. Conjugate addition of dialkylcopper-lithium reagents to .alpha.,.beta.-acetylenic esters
作者:Elias J. Corey、John A. Katzenellenbogen
DOI:10.1021/ja01035a045
日期:1969.3
Highly stereoselective isomerization of ynones to conjugated dienones catalyzed by transition-metal complexes
作者:Dawei Ma、Yihua Yu、Xiyan Lu
DOI:10.1021/jo00266a021
日期:1989.3
[2,3] Wittig rearrangement of nonracemic propargyl ethers leading to allenes of high stereochemical integrity
作者:James A. Marshall、Edward D. Robinson、Antonio Zapata