Wolff rearrangement of (1-diazo-2-oxoalkyl) silanes
作者:Ralf Brückmann、Klaus Schneider、Gerhard Maas
DOI:10.1016/s0040-4020(01)89498-9
日期:1989.1
(1-diazo-2-oxoalkyl) silanes 6a-1 results in Wolffrearrangement yielding silyl ketenes 8a-1. From (1-diazo-3,3-dimethyl-2-oxobutyl) silanes 6c-f, 2-silyl-cyclobutanones 9c-f are formed as by-products, arising from intramolecular C/H insertion of the acyl carbene intermediate. Irradiation of diazo-triisopropylsilyl-acetamide 6m yields only β-lactam 16 and γ-lactam 17. Wolffrearrangement also takes place on copper triflate
Aryl Trialkylsilyl Ketenes: Acid-Catalyzed Synthesis from 1-Aryl-2-diazo-2-trialkylsilylethanones and Their Conversion into 3-Silyl-1-silyloxyallenes
作者:Stefan M. Bucher、Ralf Brückmann、Gerhard Maas
DOI:10.1002/ejoc.200800524
日期:2008.9
Aryl-substituted α-silyl α-diazo ketones are readily transformed into aryl silyl ketenes in the presence of a catalytic amount of triflic acid. Thus, a convenient method to prepare these silyl ketenes becomes available, which combines two steps, silylation of an aryl diazomethyl ketone and acid-induced Wolff rearrangement of the formed α-silyl α-diazo ketone, in a one-pot procedure. It appears that
Efficient, general synthesis of silylketenes via an unusual rhodium mediated Wolff rearrangement
作者:Stephen P. Marsden、Wai-Kit Pang
DOI:10.1039/a902549i
日期:——
Silylketenes bearing a range of substituents (alkyl, alkenyl, aryl, heteroaryl) are prepared by an unusual rhodium mediated Wolff rearrangement of the corresponding silyl diazo ketones.
Aldol-type addition of alpha-triethylsilyl-alpha-diazoacetone was achieved under nucleophilic activation by tetrabutylammonium fluoride (TBAF). The use of a semi-stoichiometric amount of TBAF (protocol P1) provided the corresponding beta-hydroxy-alpha-diazoacetone as the sole product. Alternatively, the use of a catalytic amount of TBAF led to a mixture of beta-hydroxy- and beta-silyloxy-alpha-diazoacetone products, which was cleanly desilylated with Et3N center dot 3HF (protocol P2). The weakly basic conditions employed tolerate a wide range of substrates and constitute a high-yielding, convenient complementary procedure to the low-temperature LDA-promoted aldol-type addition of diazoacetone.
BRUCKMANN, RALF;SCHNEIDER, KLAUS;MAAS, GERHARD, TETRAHEDRON, 45,(1989) N7, C. 5517-5530