Ring enlargement with diazomethane

VI,34. RING ENLARGEMENT WITH DIAZOMETHANE CYCLOHEPTANONE FROM CYCLOHEXANONE... 

Jones and Price"" therefore concluded that diazomethane ring enlargement of 17j5-hydroxy-5a-androstan-3-one (Ic) proceeds with predominately C3—C4. migration, in contrast to the 5a-cholestane series which differs from (Ic) only in the 17-substituent. 

Dialkylanilines, pure, from commercial products, 572 Di-n-amyl ether, 313 Di-iso-amyl ether, 313 Di-n-amyl ketone, 340 Diazoaminobenzene, 622, 627 Diazoamino-aminoazo rearrangement, 622J, 626, 627 Diazo ketone, 903, 904, 905 Diazomethane, 946, 967, 968, 969-972 determination of, 972 methylation with, 973 precautions in the use of, 968, 969 ring enlargement with, 946J, 947 Diazonium fluoborates, 594, 610, 611, 612, 613... 

CHg linkage. Hydrogenation of this compound yields, however, a hydrocarbon CuHaa, IR-data of which are very similar to but not identical with the curve of i-butylcycloheptane, obtained by synthesis (84) from 4-i-butylcyclohexanone by ring enlargement with diazomethane, followed by Kishner-Wolf reduction of the i-butyl-cycloheptanone. 

Reaction of cyclic ketones with diazoraethane leads to ring enlargement. Thus cyctohexanone (I) (1 mol) and diazomethane (1 mol) give /oheptanone (II) in about 60 per cent, yield together with a little epoxide (III) as by product and some cj/cioootanone (IV) resulting from further reaction of cyctoheptanone with diazomethane. ... 

Ring enlargement of 17jS-hydroxy-5jff-androstan-3-one (12) with diazomethane gives 17j8-hydroxy-A-homo-5j8-androstan-3-one (13) and 17)8-hydroxy-A-homo-5j8-androstan-4-one (14) in a total yield of 72%. 

B-norketone (119) by enlarging ring A with diazomethane to give A-homo-B-norketone (120). Wolff-Kishner reduction of (120) gave hydrocarbon (118) identical to the product from ketone (116a). 

Cyclopropane derivatives, including spiropentanc, have proven to be virtually inert towards carbenes,1 For this reason, no literature report that describes cyclobutane synthesis from a C3 and a Cj building block by ring enlargement of cyclopropanes exists. However, due to the partial p character, as well as the increasing reactivity caused by its strain, the central bond of bicyclo[1.1.0]butane (l)2 has been found to react with carbenes.1 Photolysis of diazomethane in the presence of bicyclo[1.1.0]butane (1) at — 50 C provides a mixture of several compounds. The major fraction of the material (80%) was analyzed by means of NMR spectrometry and found to consist of penta-1,4-diene (2, 21%) and bicyclo[l.l.l]pentane (3, 1%), plus several other known compounds as well as some unidentified products.3 The mechanistic pathway for the formation of bicyclo[l.l.l]pentane (3) has not been addressed in detail, but it is believed that a diradical intermediate is involved, as shown below.3... 

In situ ring enlargement of intermediate cyclopropanones to silyl- and germyl-substituted cyclobutanones was achieved by treatment of silyl- and germyl-substituted ketenes 12 with an excess of diazomethane.129,130... 

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