Weygand/Hilgetag Preparative Organic Chemistry

C-C linkage by replacement of nitrogen by carbon 967
(page 936); and use of dialkyl sulfates for alkylation by the Fittig reaction
(page 938) and for alkylation of Grignard reagents (page 940), of compounds
containing reactive methylene groups (pages 913, 920) of cyanides (page 923),
and of acetylides (page 931).
VI. C-C linkage by replacement of nitrogen by carbon
1. Removal of elemental nitrogen
a. Reactions of diazo esters
There are various methods of forming new carbon-carbon bonds that involve
loss of nitrogen. Some have been described in preceding Sections, e.g., the
reaction of aldehydes and ketones with diazomethane (page 907); the original
literature should be consulted for others, such as the reaction for diazomethane
with compounds containing reactive methylene groups (formation of methyl
derivatives); 777 ' 778 yet others have now only historical interest (see, e.g.,
Gomberg and Berger 779 ). The following are some of the more important of
the remainder.
Ethyl diazoacetate reacts with benzene with loss of nitrogen and formation
of ethyl norcara-2,4-diene-7-carboxylate. 780
Substituted acetic acids are formed on irradiation of ethyl diazoacetate in
admixture with cycloalkanes: 781
f N2CHCOOC2H5 -> N2 + I VCH2COOC2HS
Alkyl halides and ethyl diazoacetate give higher #-halo aliphatic acids,
e.g., ethyl 2-bromo-4-pentenoate from allyl bromide in 68-74% yield. 782
Acetals react with ethyl diazoacetate in the presence of boron trifluoride;
benzaldehyde diethyl acetal affords ethyl 2,3-diethoxy-3-phenylpropionate: 783
C6H5CH(OC2H5) + N2CHCOOC2H5
• C6H5—CH—CH—COOC2H5
C2H5O OC2H5
An analogous reaction occurs with dithioacetals, giving bis(methylthio)
compounds. 783 ' 784
b. Reactions of diazo ketones
Diazo ketones can cyclize with loss of nitrogen: 2-[o-(diazoacetyl)phenyl]naphthalene
is converted in chrysenol when treated with glacial acetic and sulfuric
acid. 785
777 R. Daniels and O. L. Salerni, Proc. Chem. Soc, 1960, 286; K. Syhora, Collect. Czech.
Chem. Commun., 26, 107 (1961).
778 A. Wettstein, Helv. Chim. Acta, 27, 1803 (1944); J. Attenburrow, J. E. Connett,
W. Graham, J. F. Oughton, A. C. Ritchie, and P. A. Wilkinson, /. Chem. Soc, 1961, 4547.
779 M.Gomberg andH. W.Berger,Ber. Deut. Chem. Ges., 36,1090 (1903); 30, 2043 (1897).
780 N. Braren and E. Buchner, Ber. Deut. Chem. Ges., 34, 989 (1901).
781 W. von E. Doering and L. H. Knox, /. Amer. Chem. Soc, 78, 4947 (1956).
782 I. A. Dyakonov and N. B. Vinogradova, Zh. Obshch. Khim., 21, 851 (1951); Chem.
Abstr., 46, 440 (1952).
783 A. Schonberg and K. Praefcke, Tetrahedron Lett., 1964, 2043.
784 A. Schonberg and K. Praefcke, Chem. Ber., 100, 778 (1967).
785 J. W. Cook and R. Schoental, /. Chem. Soc, 1945, 288.