Spirovetivanes from fulvenes

Buechi, George; Berthet, D.; Decorzant, René; Grieder, A.; Hauser, Arnold

doi:10.1021/jo00881a034

Cited by 52 publications

(12 citation statements)

References 4 publications

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“…Interestingly, 11 was structurally related to a desisopropyl spirovetiv-3-en-7-one 16 that Büchi et al 17,18 had reported to also possess a typical vetiver odor: 6,10-dimethylspiro[4.5]dec-6-en-2-one (8). Although structurally related to some of the constituents of vetiver, 8 has not yet been found in essential oils.…”

Section: Methodsmentioning

confidence: 99%

Design, Synthesis and Structure-Odor Correlation of Novel Spiro[4.5]-decan-2-ones

Kraft¹,

Cadalbert²

2002

Synthesis

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Dehydration and Rupe rearrangement of 2-(3,3-dimethylcyclohexyl)hex-3-yne-2,5-diol (9) furnished as a 3% byproduct the intense vetiver-like smelling 4,7,7-trimethyl-1-methylenespiro[4.5]decan-2-one (11). Motivated by the commercial importance of vetiver oil and the lack of synthetic substitutes as well as the lack of insight into the structural requirements for vetiver odorants, an efficient synthetic route to vetiver-like smelling compounds was developed. It consists of Wittig-Horner-Emmons reaction of diverse cycloalkanones with triethyl 2-phosphonopropionate, subsequent Grignard reaction with in situ conversion to the trienolate, and classical Nazarov cyclization of the resulting dienones. This route not only leads to 11 in 61% yield in the final Nazarov cyclization, but also to 16 analogs, which provide insight into both, the Nazarov reaction and the structure-odor relationship of vetiver odorants. Other vetiver-like smelling compounds discovered include (1RS,4SR,5SR)-1,4,7,7-tetramethylspiro[4.5]decan-2-one (16), 4-methyl-1-methylenespiro[4.6]undecan-2-one (30) and 4-methyl-1-methylenespiro[4.7]dodecan-2-one (31).

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Section: Methodsmentioning

confidence: 99%

Design, Synthesis and Structure-Odor Correlation of Novel Spiro[4.5]-decan-2-ones

Kraft¹,

Cadalbert²

2002

Synthesis

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“… 12 The extent of this polarization is manifested in the relatively more downfield shift of the protons on C6 in the NMR spectra, 13 as well as the ease of attack of various, mostly hard nucleophiles at the exocyclic double bond. 14 We previously tested the competing reactivities of a variety of nucleophiles toward C6 vs C7 carrying a leaving group on 6-chloromethyl-6-methylfulvene, whereas thiolate, azide, and thiocyanate ions 3a and benzylamine 3b undergo S N 2 attack at the chloromethyl group in 1 , and CN – and CH 3 Li 3a exclusively attack C6, giving rise to spiro[2.4]hepta-4,6-diene derivatives (Scheme 1 ). 3 Recently, we have extended these reactions to competing C6 vs C7 attacks by various Michael donors.…”

Section: Introductionmentioning

confidence: 99%

Effect of Allylic Groups on S_N2 Reactivity

et al. 2014

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The activating effects of the benzyl and allyl groups on SN2 reactivity are well-known. 6-Chloromethyl-6-methylfulvene, also a primary, allylic halide, reacts 30 times faster with KI/acetone than does benzyl chloride at room temperature. The latter result, as well as new experimental observations, suggests that the fulvenyl group is a particularly activating allylic group in SN2 reactions. Computational work on identity SN2 reactions, e.g., chloride– displacing chloride– and ammonia displacing ammonia, shows that negatively charged SN2 transition states (tss) are activated by allylic groups according to the Galabov–Allen–Wu electrostatic model but with the fulvenyl group especially effective at helping to delocalize negative charge due to some cyclopentadienide character in the transition state (ts). In contrast, the triafulvenyl group is deactivating. However, the positively charged SN2 transition states of the ammonia reactions are dramatically stabilized by the triafulvenyl group, which directly conjugates with a reaction center having SN1 character in the ts. Experiments and calculations on the acidities of a variety of allylic alcohols and carboxylic acids support the special nature of the fulvenyl group in stabilizing nearby negative charge and highlight the ability of fulvene species to dramatically alter the energetics of processes even in the absence of direct conjugation.

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“…With excess pyrrolidine in MeOH, desulfenylation results in the formation of acrolein and methyl thiolate. The latter, being a strong nucleophile, attacks the fulvene formed during the reaction at the 6-position, as fulvenes are prone to attack by nucleophiles at the exocyclic double bond 6,14 (Figure 4). …”

Section: Resultsmentioning

confidence: 99%

An expedient synthesis of 6-Vinylfulvene

et al. 2013

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6-Vinylfulvenes constitute a class of fulvenes that are difficult to access due to the lack of a general method for their synthesis. In particular, the unsubstituted parent system has been very difficult to obtain by existing methods.In this communication we describe a convenient 3-step protocol for the synthesis of the title compound by way of sulfide oxidation and subsequent sulfoxide elimination.

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Spirovetivanes from fulvenes

Cited by 52 publications

References 4 publications

Design, Synthesis and Structure-Odor Correlation of Novel Spiro[4.5]-decan-2-ones

Design, Synthesis and Structure-Odor Correlation of Novel Spiro[4.5]-decan-2-ones

Effect of Allylic Groups on S_N2 Reactivity

An expedient synthesis of 6-Vinylfulvene

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Spirovetivanes from fulvenes

Cited by 52 publications

References 4 publications

Design, Synthesis and Structure-Odor Correlation of Novel Spiro[4.5]-decan-2-ones

Design, Synthesis and Structure-Odor Correlation of Novel Spiro[4.5]-decan-2-ones

Effect of Allylic Groups on SN2 Reactivity

An expedient synthesis of 6-Vinylfulvene

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Product

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Effect of Allylic Groups on S_N2 Reactivity