Isocyclics, bicyclic

Butyn-2-one undergoes tandem [3+2] cycloadditions of allyltriisopropylsilane to give a bicyclo[3.3.0]octane as a mixture of three possible diastereomers in a good yield (Scheme 10.169) [468]. The use of a reduced amount of the allylsilane forms a silylated cyclopentene as a minor product. This indicates that the 1 1 cycloadduct is the precursor of the bicyclic product. In contrast, the ZnL or Me2AlCl-promoted reaction of 3-butyn-2-one with an isocyclic allyltrimethylsilane affords a [2+2] adduct wifhout [3+2] adducts [448a, 469] (vide infra). 

The reaction has been shown to be of very broad scope with a multitude of nucleophiles Nu such as imides.23,24,29,32,33,36,37,42 amines,10,32 cyanide,25,32 hydroxide,10,32 alkox-ide,10,26,32 electron-rich isocyclic or heterocyclic aromatic compounds,28 carboxamides,31 lactams,31 ureas,31 sulfonamides,31 cyanate,31 formate (to give products with Nu = H),34 C-H acidic compounds,35 hydrazines and hydrazides,38 and sulfinates.38 The amino group NR R2 of cyclopropane-1,1-diamines and the nucleophile Nu in bicycles 8, 9 or 12, respectively, can be easily replaced with other nucleophiles Nu, such as water,10,32,33 alkoxide,10,32-34,42 Grignard compounds,27,42 amines,29,30,36,37,42,43 cyanide,29,33,42,44 hydride,34,42,44 and C-H acidic compounds39-41,43,44 (see Section 5.2.1.). Therefore, it is currently the most important method for the preparation of substituted bicyclic cyclopropylamines. The toxic and costly reagent methyl fluorosulfate can be avoided in a modified synthetic route, which instead of the fluorosulfate 5 proceeds via the corresponding tetraphenylborate, hexafluorophosphate, or (most conveniently) via the tosylate.23 The different steps of the method can often be combined in a one-pot procedure. Results are summarized in Table 3. 

Within the groups defined under 1. open chain radicals are followed by semicyclic, isocyclic, heterocyclic and bicyclic systems. Only those systems are termed cyclic , in which different 7t-centers are connected to a cycle. Radicals with partial structures like (7) and (8), where the same 7t-center is the beginning and the end of a cycle, are treated together with di-alkyl substituted species. 

Methyl 2,5-dihydro-4-carbomethoxy-2-thiopheneacetate added at 180° to excess butadiene in the presence of hydroquinone, the intermediate refluxed 18 hrs. with Raney-Ni W 5 in methanol, then saponified by refluxing 40 hrs. with aq.-ethanolic KOH diacid. Overall Y 52%. - This synthesis can be used for the construction of trans-fused bicyclic isocyclics with angular methyl groups. F. e. s. G. Stork and P. L. Stotter, Am. Soc. 91, 7780 (1969) stereospecific diene synthesis, effect of substituents, s. P. C. Jain, Y. N. Mukerjee, and N. Anand, Chem. Commun. 1971, 303. 

Nickel complex compound Tetracyclic from bicyclic isocyclics s. 18, 780... 

Potassium hydrogen sulfate kaolin Skeletal rearrangement of bicyclic isocyclics... 

Bicyclic from monocyclic isocyclics by thermal isomerization... 

Series I. Aliphatic compounds Series II. Carbo-isocyclic non-condensed compounds Series III. Carbo-isocyclic condensed compounds Vol. 12. Bicyclic compounds Vol. 13. Tricyclic compounds Vol. 14. Tetra and higher cyclic compounds Series IV. Heterocyclic compounds General Indexes... 

---