Chemical Consequences of Long-Range Orbital Interactions in Norbornane-Based 1,4-Diol Monosulfonate Esters

Base-Induced Rearrangement of Perhydronaphthalene-1,4-diol Monosulfonate Esters to 11-Oxatricyclo[5.3.1.02,6]undecanes. Total Synthesis of Furanether B

“…The formation of 5 can easily be explained by intramolecular trapping of the positive charge by the alkoxide substituent in the rearranged intermediate 16 . Because of the presence of a protected hydroxyl group at C(8) in 16 , the possible interference of a Grob fragmentation is blocked 1b…”

“…All reagents were purchased from Aldrich or Acros and were used without further purification, unless otherwise stated. The ketone 8 was prepared from the known Robinson annulation product 7 10 as previously described 1b. The compounds 3 ,1b 4 , 7a, 18 ,7a 19 , 7a, 20 ,7a and 31 8 were characterized before.…”

“…From our previous work on the chemical consequences of long-range orbital interactions in stereochemically rigid 1,4-diol monosulfonate esters, it is known that elimination, rearrangement, and homofragmentation are the preferred pathways by which these compounds react upon treatment with a strong base and alloaromadendrane sesquiterpenes, whereas the homofragmentation reaction has been used as the key step in the synthesis of α-santalanes …”

“…While the reaction of mesylate 1 with sodium tert -amylate in refluxing benzene produces selectively the homofragmentation product 2 , the corresponding reaction with lithium tert -amylate as base results in a ca. 2:1 mixture of 2 and the rearranged tricyclic ether 3 , respectively 1b. The co-occurrence of homofragmentation and rearrangement in the reaction of 1 with lithium tert -amylate has been explained by a decrease of the electron-donating ability of the alkoxide group with Li + as counterion .…”

Neighboring amide participation in the Fenton oxidation of a sulfide to sulfoxide, vinyl sulfide and ketone relevant to oxidation of methionine thioether side chains in peptides

“…13, fully characterized it, and compared its elution and its MS/MS profile with that of product 11 obtained after the Fenton oxidation of 2. Epimerization of the known endo-ester ketal 14 44 with sodium methoxide afforded predominantly the exo-acid ketal 15 (Fig. 13B) which was hydrolyzed quantitatively with aqueous hydrochloric acid to keto exo acid 16 (Fig.…”