2-(Trimethylsilyloxy)furan as a dianion equivalent: a two-step synthesis of functionalized spirocyclic butenolides.
[reaction: see text] The use of 2-(trimethylsilyloxy)furan derivatives as dianion equivalents leads to a general and connective spiroannulation protocol for the efficient preparation of spirocyclic butenolides.
Highly diastereoselective vinylogous Mukaiyama aldol reaction of α-keto phosphonates with 2-(trimethylsilyloxy)furan catalyzed by Cu(OTf)2.
The diastereospecific formation of δ-hydroxyalkylbutenolide phosphonate has been achieved via a vinylogous Mukaiyama aldol reaction. The reaction was performed using α-ketophosphonate 1 and 2-(trimethylsilyloxy)furan 2 mediated by Cu(OTf)(2) and 2,2,2-trifluoroethanol as additive in CH(2)Cl(2). The reaction proceeds rapidly and affords the corresponding 5-(hydroxy(aryl)methyl) furan-2(5H)-one phosphonates 3 in high yields with good to excellent diastereoselectivities (d.r. up to >99 : 1). 5-(Hydroxy(alkyl)methyl)furan-2(5H)-one phosphonates could also be obtained with good diastereoselectivities.
The Mound on the Mount: A Possible Solution to the Problem with Jerusalem
Following Knauf's suggestion (2000), the article raises the possibility that in most periods in the second and first millennia BCE the main built-up area of Jerusalem was limited to a mound on the Temple Mount. This mound, which may have covered an area of five hectares and more, was boxed-in under the Herodian platform. At these periods activity in the City of David ridge was restricted to the area near the Gihon spring. In the Iron IIB and late Hellenistic Periods the fortified settlement expanded simultaneously to both the City of David ridge and the southwestern hill. In these two periods there was no need to fortify the western side of the City of David, as this line ran in the middle of the city.