Practical synthesis of allylsilanes from 1-benzenesulfonyl-2-trimethylsilylethane

Enantioselektive Totalsynthese der hoch oxygenierten 1,10‐seco‐Eudesmanolide Eriolanin und Eriolangin

“…Durch Behandlung von 9 mit β‐Chlorethansulfonsäurechlorid13 und Triethylamin wurde in einem Dominoprozess aus Eliminierung, Veresterung und intramolekularer Diels‐Alder‐Reaktion ein Gemisch aus 10 und einem weiteren exo ‐Sultonisomer gebildet, aus dem nach thermischer Äquilibrierung reines 10 in ausgezeichneter Ausbeute isoliert werden konnte 8. Die Überführung von 10 in das Methylencyclohexen 13 gelang mittels einer sequenziellen Transformation aus Eliminierung, alkoxiddirigierter 1,6‐Addition des Lithiosilans 12 14, 15 und Desulfurierung unter Methylenierung im Eintopfverfahren 16. In einem Schritt wurden so die Präfunktionen für ein γ‐Lacton enthüllt, mit dem 1,3‐Dien eine Aktivierung für eine 1,4‐Dioxygenierung geschaffen und der primäre Alkohol für eine Seitenkettenverlängerung freigelegt.…”

Oxidative Fragmentations of 2-(Trimethylsilyl)ethyl Sulfoxides − Routes to Alkane-, Arene-, and Highly Substituted 1-Alkenesulfinyl Chlorides

“…Upon completion, the mixture was fractionally distilled or chromatographed to afford pure sulfide. The syntheses of sulfides 1a, [32] b, e, f, k, [33] g, [26] and j [31] by this method have been reported previously. The following sulfides have not been reported.…”

“…Sulfoxide 2j, prepared by this method, has been reported. [31] Phenyl 2-(Trimethylsilyl)ethyl Sulfoxide (2a): The reaction of sulfide 1a (4.32 g, 17.7 mmol) with NaIO 4 (3.95 g, 17.7 mmol) afforded sulfoxide 2a [32] (4.51 g, 98%) after chromatography.…”

“…Sulfides 1 were obtained through radical addition of a thiol to trimethyl(vinyl)silane as described previously by us [31] and others. [26,32] The overall approach to sulfoxides 2 is indicated in the first two steps of Scheme 2, with the yields presented in Table 1. [31,33] Although treatment of simple alkyl-bearing sulfoxides with sulfuryl chloride would be expected to afford the product of α-chlorination, [34,35] it was quickly discovered that the 2-(trimethylsilyl)ethyl group induced a different behavior.…”

Enantioselective Total Synthesis of the Highly Oxygenated 1,10‐seco‐Eudesmanolides Eriolanin and Eriolangin

“…By treatment of 9 with β‐chloroethanesulfonic acid chloride13 and triethylamine, a mixture of 10 and a further exo sultone isomer was formed in a domino process consisting of elimination, esterification, and intramolecular Diels–Alder reaction, from which pure 10 could be isolated in excellent yield after thermal equilibration 8. Conversion of 10 to methylenecyclohexene 13 succeeded by a sequential transformation consisting of elimination, alkoxide‐directed 1,6‐addition of lithiosilane 12 ,14, 15 and desulfurization with simultaneous methylenation in a one‐pot procedure 16. In a single synthetic operation, the prefunctions for a γ‐lactone were unfolded, activation for 1,4‐dioxygenation was created by virtue of the 1,3‐diene, and the primary hydroxy group was liberated for side‐chain elongation.…”