Diastereoselective alkylation of the dianion of 5-ethoxy-4(S)-hydroxy-1-isopropyl-2-pyrrolidinone; Synthesis of enantiomerically pure azabicycles
作者:Wim J. Klaver、Henk Hiemstra、W.Nico Speckamp
DOI:10.1016/s0040-4039(01)81047-9
日期:1987.1
The alkylation of the dianion of the title compound () readily prepared from (S)-malic acid, with ω-iodo-1-trimethylsilyl-2-alkynes (-) occurs with high trans-selectivity with respect to the hydroxyl function. The products (-) cyclize in formic acid to enantiomerically pure azabicyclic allenes (-), one of which () might be a suitable precursor to peduncularine ().
Silicon-assisted synthesis of bridged azabicyclic systems via N-acyliminium intermediates
作者:Wim J. Klaver、Henk Hiemstra、W.Nico Speckamp
DOI:10.1016/s0040-4020(01)90113-9
日期:1988.1
with five- and six-membered cyclic N-acyliminium ion precursors lead to bridged azabicyclic compounds (Table I). Neat formic acid is the reaction medium of choice in most cases. The cyclization reactions take place with complete regioselectivity. 2-Propynylsilanes are more reactive than allylsilanes. An ordinary olefin reacts poorly. The cyclization products can be useful for the synthesis of γ- and
The total synthesis of the marine sesquiterpenes neolemnanyl acetate (1) and neolemnane (2) is reported. An intramolecular allylsilane addition to a conjugated dienone is used to assemble the basic 6,8-fused skeleton. Functionalization of the cyclooctane ring was achieved by means of a regiospecific photooxygenation.
MAJETICH, GEORGE;LOWERY, DERRIC;KHETANI, VIKRAM;SONG, JEE-SEOP;HULL, KENN+, J. ORG. CHEM., 56,(1991) N2, C. 3988-4001