[4+2] Cycloadditions of 2-(trialkylsilyloxy)-allylidenecyclopropanes - synthesis of spiro[2.5]octan-5-ones

Thies Thiemann; Stephan Kohlstruk; Gerhard Schwär; Armin de Meijere

doi:10.1016/0040-4039(91)80812-K

[4+2] Cycloadditions of 2-(trialkylsilyloxy)-allylidenecyclopropanes - synthesis of spiro[2.5]octan-5-ones

Thies Thiemann
, Stephan Kohlstruk
, Gerhard Schwär
, Armin de Meijere

Research output: Contribution to journal › Article › peer-review

18 Citations (Scopus)

Abstract

The previously unknown 2-(trialkylsilyloxy)allylidenecyclopropanes 2a-d have been prepared by silyl-enolization of the easily available cyclopropylidenealkanones 1-R¹ in good yields. Dienes 2a-d readily react with a variety of dienophiles at temperatures ranging from 0 to 130°C to give derivatives 5-10 of 5-(trialkylsilyloxy)spiro-[2.5]oct-4-ene or the corresponding hydrolysis products 10, 12. Weak dienophiles like cyclohexenone and cyclopentenone give spiro[2.5]octan-5-one derivatives only under BF₃ catalysis and with poor yields.

Original language	English
Pages (from-to)	3483-3486
Number of pages	4
Journal	Tetrahedron Letters
Volume	32
Issue number	29
DOIs	https://doi.org/10.1016/0040-4039(91)80812-K
Publication status	Published - Jul 15 1991
Externally published	Yes

Keywords

BF catalysis
Diels-Alder reactions
Ring strain and donor activated dienes
spirocyclopropane mimic of gem-dimethyl groups

ASJC Scopus subject areas

Biochemistry
Drug Discovery
Organic Chemistry

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10.1016/0040-4039(91)80812-K

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@article{117fdee6db304f3681538bb6368b2569,

title = "[4+2] Cycloadditions of 2-(trialkylsilyloxy)-allylidenecyclopropanes - synthesis of spiro[2.5]octan-5-ones",

abstract = "The previously unknown 2-(trialkylsilyloxy)allylidenecyclopropanes 2a-d have been prepared by silyl-enolization of the easily available cyclopropylidenealkanones 1-R1 in good yields. Dienes 2a-d readily react with a variety of dienophiles at temperatures ranging from 0 to 130°C to give derivatives 5-10 of 5-(trialkylsilyloxy)spiro-[2.5]oct-4-ene or the corresponding hydrolysis products 10, 12. Weak dienophiles like cyclohexenone and cyclopentenone give spiro[2.5]octan-5-one derivatives only under BF3 catalysis and with poor yields.",

keywords = "BF catalysis, Diels-Alder reactions, Ring strain and donor activated dienes, spirocyclopropane mimic of gem-dimethyl groups",

author = "Thies Thiemann and Stephan Kohlstruk and Gerhard Schw{\"a}r and Meijere, \{Armin de\}",

note = "Funding Information: The deactivateda nd more highly substituted3 -acetoxy-2-methylcyclopentenonde id not react with 2a at all. In the latter reactlon the only product isolated was 17 (28\% yield), apparently formed from the [4+2] cycloadduct of 2a onto 1-H arismg from hydrolysis of 2a. Although formally l,l-disubstituted, the previously unknown 2-(trialkylsilyloxy)allylidenecyclopropanes2 are activatedb oth by ring strain and donor substitution.T heir cycloadducts 5-12 can be used as a mlmlc of the correspondmg skeletons with a gem-dimethyl umt m place of the spirocyclopropaneg roup. In fact, the latter can generally be transformedi ntn a gem-dlmethyl unit by catalytic hydrogenation,a s has been demonstrateda number of tlmes.13 Acblowledgenzenfs This work was financially supportedb y the Deutsche Forschungsgemeinschaft( Projekt Me 405/14-1,2,3) and the Fonds der Chemlschen Industrie as well as BASF, BAYER, HOECHST and HtiS AG through generous gifts of chemicals Stephan Kohlstruk IS grateful to the Konrad Adenauer Foundation for a graduatef ellowship (Doktoranden-Stlpendlum).",

year = "1991",

month = jul,

day = "15",

doi = "10.1016/0040-4039(91)80812-K",

language = "English",

volume = "32",

pages = "3483--3486",

journal = "Tetrahedron Letters",

issn = "0040-4039",

publisher = "Elsevier Ltd",

number = "29",

}

TY - JOUR

T1 - [4+2] Cycloadditions of 2-(trialkylsilyloxy)-allylidenecyclopropanes - synthesis of spiro[2.5]octan-5-ones

AU - Thiemann, Thies

AU - Kohlstruk, Stephan

AU - Schwär, Gerhard

AU - Meijere, Armin de

N1 - Funding Information: The deactivateda nd more highly substituted3 -acetoxy-2-methylcyclopentenonde id not react with 2a at all. In the latter reactlon the only product isolated was 17 (28% yield), apparently formed from the [4+2] cycloadduct of 2a onto 1-H arismg from hydrolysis of 2a. Although formally l,l-disubstituted, the previously unknown 2-(trialkylsilyloxy)allylidenecyclopropanes2 are activatedb oth by ring strain and donor substitution.T heir cycloadducts 5-12 can be used as a mlmlc of the correspondmg skeletons with a gem-dimethyl umt m place of the spirocyclopropaneg roup. In fact, the latter can generally be transformedi ntn a gem-dlmethyl unit by catalytic hydrogenation,a s has been demonstrateda number of tlmes.13 Acblowledgenzenfs This work was financially supportedb y the Deutsche Forschungsgemeinschaft( Projekt Me 405/14-1,2,3) and the Fonds der Chemlschen Industrie as well as BASF, BAYER, HOECHST and HtiS AG through generous gifts of chemicals Stephan Kohlstruk IS grateful to the Konrad Adenauer Foundation for a graduatef ellowship (Doktoranden-Stlpendlum).

PY - 1991/7/15

Y1 - 1991/7/15

N2 - The previously unknown 2-(trialkylsilyloxy)allylidenecyclopropanes 2a-d have been prepared by silyl-enolization of the easily available cyclopropylidenealkanones 1-R1 in good yields. Dienes 2a-d readily react with a variety of dienophiles at temperatures ranging from 0 to 130°C to give derivatives 5-10 of 5-(trialkylsilyloxy)spiro-[2.5]oct-4-ene or the corresponding hydrolysis products 10, 12. Weak dienophiles like cyclohexenone and cyclopentenone give spiro[2.5]octan-5-one derivatives only under BF3 catalysis and with poor yields.

AB - The previously unknown 2-(trialkylsilyloxy)allylidenecyclopropanes 2a-d have been prepared by silyl-enolization of the easily available cyclopropylidenealkanones 1-R1 in good yields. Dienes 2a-d readily react with a variety of dienophiles at temperatures ranging from 0 to 130°C to give derivatives 5-10 of 5-(trialkylsilyloxy)spiro-[2.5]oct-4-ene or the corresponding hydrolysis products 10, 12. Weak dienophiles like cyclohexenone and cyclopentenone give spiro[2.5]octan-5-one derivatives only under BF3 catalysis and with poor yields.

KW - BF catalysis

KW - Diels-Alder reactions

KW - Ring strain and donor activated dienes

KW - spirocyclopropane mimic of gem-dimethyl groups

UR - https://www.scopus.com/pages/publications/0025780167

UR - https://www.scopus.com/pages/publications/0025780167#tab=citedBy

U2 - 10.1016/0040-4039(91)80812-K

DO - 10.1016/0040-4039(91)80812-K

M3 - Article

AN - SCOPUS:0025780167

SN - 0040-4039

VL - 32

SP - 3483

EP - 3486

JO - Tetrahedron Letters

JF - Tetrahedron Letters

IS - 29

ER -

[4+2] Cycloadditions of 2-(trialkylsilyloxy)-allylidenecyclopropanes - synthesis of spiro[2.5]octan-5-ones

Abstract

Keywords

ASJC Scopus subject areas

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