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Spirocyclopropanated Bicyclopropylidenes: Straightforward Preparation, Physical Properties, and Chemical Transformations
Author(s) -
de Meijere Armin,
von Seebach Malte,
Zöllner Stefan,
Kozhushkov Sergei I.,
Belov Vladimir N.,
Boese Roland,
Haumann Thomas,
BenetBuchholz Jordi,
Yufit Dmitrii S.,
Howard Judith A. K.
Publication year - 2001
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/1521-3765(20010917)7:18<4021::aid-chem4021>3.0.co;2-e
Subject(s) - biochemical engineering , engineering
Perspirocyclopropanated bicyclopropylidene ( 6 ) was prepared in three steps from 7‐cyclopropylidenedispiro[2.0.2.1]heptane ( 4 ) (24 % overall) or, more efficiently, through dehalogenative coupling of 7,7‐dibromo[3]triangulane ( 15 ) (82 %). This type of reductive dimerization turned out to be successful for the synthesis of ( E )‐ and ( Z )‐bis(spiropentylidene) 14 (67 %) and even of the “third‐generation” spirocyclopropanated bicyclopropylidene 17 (17 % overall from 15 ). Whereas the parent bicyclopropylidene 1 dimerized at 180 °C to yield [4]rotane, dimerization of 6 at 130 °C under 10 kbar pressure occured only with opening of one three‐membered ring to yield the polyspirocyclopropanated (cyclopropylidene)cyclopentane derivative 19 (34 % yield), and at the elevated temperature the polyspirocyclopropanated 2‐cyclopropylidene[3.2.2]propellane derivative 20 (25 % yield). Perspirocyclopropanated bicyclopropylidene 6 and the “third‐generation” bicyclopropylidene 17 gave addition of bromine, hydrogen bromide, and various dihalocarbenes without rearrangement. The functionally substituted branched [7]triangulane 28 and branched dichloro‐ C 2v ‐[15]triangulane 32 were used to prepare the perspirocyclopropanated [3]rotane ( D 3h ‐[10]triangulane) 49 (six steps from 6 , 1.4 % overall yield) and the C 2v ‐[15]triangulane 51 (two steps from 17 , 41 % overall). Upon catalytic hydrogenation, the perspirocyclopropanated bicyclopropylidene 6 yielded 7,7′‐bis(dispiro[2.0.2.1]heptyl) ( 52 ) and, under more forcing conditions, 1,1′‐bis(2,2,3,3‐tetramethylcyclopropyl) ( 53 ). The bromofluorocarbene adduct 33 of 17 reacted with butyllithium to give the unexpected polyspirocyclopropanated 1,4‐di‐ n ‐butyl‐2‐cyclopropylidenebicyclo[2.2.0]hexane derivative 37 as the main product (55 % yield) along with the expected “third‐generation” perspirocyclopropanated dicyclopropylidenemethane 38 (21 % yield). Mechanistic aspects of this and the other unusual reactions are discussed. The structures of all new unusual hydrocarbons were proven by X‐ray crystal structure analyses, and the most interesting structural and crystal packing features are presented.