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.
Synthesis of syn,syn; anti,syn; syn,anti; and anti,anti Stereotriads from a Single Pair of Enantiomeric Reagents
作者:James A. Marshall、Jolyon F. Perkins、Mark A. Wolf
DOI:10.1021/jo00122a041
日期:1995.9
The stannanes (S)-1a, (R)-1b, and (S)-1c add to (S)- and (R)-2-methyl-3-(benzyloxy)propanal ((S)-2 and (R)-2) to afford the syn,syn (BF3 . OEt(2) promotion), syn,anti (MgBr2 . OEt(2) promotion), anti,anti (SnCl4-derived reagent in CH2Cl2), and anti,syn (SnCl4-derived reagent in hexane) stereotriad adducts 3, 4, 6, and 7.
Synthesis of enantioenriched homopropargylic alcohols through diastereoselective SE' additions of chiral allenylstannanes to aldehydes
作者:James A. Marshall、Xiao Jun Wang
DOI:10.1021/jo00030a036
日期:1992.2
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.