1,3-Dienyl β-keto esters are cyclised into bicyclolactones using the Bi(OTf)3/TfOH catalytic system. This reaction represents a rare case of simultaneous C–C and C–O bond formation at positions 1 and 3 of a 1,3-diene. Application to the synthesis of ramulosin is presented.
A Short Asymmetric Synthesis of Both Enantiomers of Ramulosin and Its Analogues
作者:Dieter Enders、Anja Kaiser
DOI:10.1055/s-1996-4195
日期:1996.2
(+)-Ramulosin, a metabolite of Pestalotia ramulosa, and its enantiomer have been synthesized in high enantiomeric purity (ee ≥ 98%) via Michael addition of metalated acetone SAMP-hydrazone (S)-1a to the acetal protected cyclic enoate 2 and subsequent diastereoselective reductive lactonization with L-Selectride. 3-Substituted hexahydroisocoumarines (3S,4aR)-5, analogues of ramulosin, were also obtained with excellent stereoselectivities (de ≥ 98%, ee ≥ 96%) using this method.
Useful route to partially saturated isocoumarins. Biomimetic syntheses of mellein, ramulosin, and epiramulosin
作者:K. Michal Pietrusiewicz、Iwona Salamonczyk
DOI:10.1021/jo00247a034
日期:1988.6
Synthesis of (±)-ramulosin via inverse type hetero-diels-alder reaction 1
作者:Klaus Vogt、Richard R. Schmidt
DOI:10.1016/s0040-4020(01)85960-3
日期:1988.1
Birch reduction of 3,4-dihydro-8-hydroxy-3-methylisocoumarin (mellein). Expeditious syntheses of (±)-ramulosin and a spruce budworm toxin
作者:Arthur G. Schultz、Yu-Jang Li
DOI:10.1016/s0040-4039(97)00296-7
日期:1997.3
A three-step conversion of (+/-)-mellein (1) to (+/-)-ramulosin (6) in 41% overall yield is described. A synthesis of the spruce budworm toxin 7 also is reponed. (C) 1997 Elsevier Science Ltd.