Grundmann ketone

Wilson and Jacob used a y-depro to nation of an allyl acrylate to generate a Z-silyl ketene acetal in a Claisen approach to 25-hydroxy vitamin D2 Grundmann ketone (Scheme 4.121) [115]. The rearrangement proceeded via the expected chair transition state to afford the desired product as a single stereoisomer. 

GRUNDMANN ALDEHYDE SYNTHESIS. Transformation of an acid into an aldehyde of the same chain length by conversion of the acid chloride via the diazo ketone to the acetoxy ketone, reduction with aluminum isopropoxide and hydrolysis to the glycol, and cleavage with lead tetraacetate. 

The Trost synthesis of calcitriol (3) is shown in Scheme 5. In a Wittig reaction, the hydroxylated Grundmann s ketone 26 (obtained by partial synthesis) is transformed into the alkenyl bromide 27 with astonishingly high diastereoselec-tivity ElZ >50 1). The chiral enyne 29, which is needed as the second building block for the coupling step, is prepared from the aldehyde 28... 

Grundmann s aldehyde synthesis also starts from acid chlorides. The latter are converted by way of the diazo ketones or acetoxy ketones into the glycols, which are subjected to cleavage by lead tetraacetate. <%,/ -Unsaturated aldehydes cannot be obtained by this method.457... 

Decomposition of diazo compounds. It is well known that diethyl fumarate is formed when ethyl diazoacetate is decomposed catalytically by copper powder.985 Grundmann applied this reaction to diazo ketones,986 obtaining a moderate yield of 3-hexene-2,5-dione from diazoacetone, and analogous products from co-diazoacetophenone and l-diazo-2-nonadecanone. 

This reaction was initially reported by Grundmann in 1936. It is the conversion of acyl chloride into aldehyde with the exact same carbon skeleton via the following consecutive steps a) treatment of acyl chloride with diazomethane to form a ketone, (b) conversion of such a ketone into ketol acetate with acetic acid, (c) reduction of ketol acetate with aluminum isopropylate, and d) hydrolysis and oxidation with lead tetraacetate. This method is especially useful in the preparation of aliphatic aldehydes with methylene-interrupted double bond(s). Although polymers might form in the preparation of highly unsaturated aldehydes during the reduction with aluminum isopropylate, the reduction from lithium aluminum hydride can eliminate such drawbacks. ... 

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